Stats

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Which is not a step in hypothesis testing?

Find the test statistic from a table.

Which of the following statements is correct?

Increasing α will make it more likely that we will reject H0, ceteris paribus.

Which is not true of the logistic regression model?

Its predictions are either 0 or 1.

Which of the following decisions could result in a Type II error for a test?

Fail to reject the null hypothesis.

The following frequency distribution shows the amount earned yesterday by employees of a large Las Vegas casino. Estimate the mean daily earnings.

$117.13

A clinic employs nine physicians. Five of the physicians are female. Four patients arrive at once. Assuming the doctors are assigned randomly to patients, what is the probability that all of the assigned physicians are female?

.0397

If the random variable Z has a standard normal distribution, then P(Z ≤ −1.72) is

.0427

The figure shows a normal N(200,50) distribution. Find the approximate shaded area.

.0668

In a right-tailed test, a statistician got a z test statistic of 1.47. What is the p-value?

.0708

If the random variable Z has a standard normal distribution, then P(1.17 ≤ Z ≤ 2.26) is

.1091

If P(A | B) = .40 and P(B) = .30, find P(A ∩ B).

.120

The probability that a certain daily flight's departure from ORD to LAX is delayed is .02. Over six months, this flight departs 180 times. What is the approximate Poisson probability that it will be delayed fewer than 2 times?

.1257

Jason wants to perform a two-tailed test for equality between two independent sample proportions. Each sample has at least 10 "successes" and 10 "failures." Jason's test statistic is −1.44. What is his p-value?

.1498

If arrivals occur at a mean rate of 3.6 events per hour, the exponential probability of waiting more than 0.5 hour for the next arrival is

.1653

If X is a discrete uniform random variable ranging from 0 to 12, find P(X ≥ 10).

.2308

Use the binomial model to find the approximate hypergeometric probability of at least two damaged flash drives in a sample of five taken from a shipment of 150 that contains 30 damaged flash drives.

.2627

John rejected his null hypothesis in a right-tailed test for a mean at α = .025 because his critical t value was 2.000 and his calculated t value was 2.345. We can be sure that

John did not commit a Type II error.

John scored 85 on Prof. Hardtack's exam (Q1 = 40 and Q3 = 60). Based on the fences, which is correct?

John is not an outlier.

Which of the following measures of fit is expressed in percent?

MAPE

Which is not assumed in ANOVA?

Population variances are known.

A sample is taken and a confidence interval is constructed for the mean of the distribution. Which value is always found at the center of the interval?

The sample mean x⎯⎯

A researcher's Excel results are shown below using Femlab (labor force participation rate among females) to try to predict Cancer (death rate per 100,000 population due to cancer) in the 50 U.S. states. Regression StatisticsMultiple R0.313422848R Square0.098233882Adjusted R Square0.079447088Standard Error32.07003698Observations50 VariableCoefficientsStandard Errort StatIntercept343.61988961.08235145.62552Femlab−2.28336590.99855319−2.28667 Which of the following statements is not true?

The standard error is too high for this model to be of any predictive use.

Which of the following statements is correct?

Statistics is the science of collecting, organizing, analyzing, interpreting, and presenting data.

Which is not a practical constraint facing the business researcher or data analyst?

Survey respondents usually will tell the truth if well compensated.

If samples are drawn from a population that is normal, a goodness-of-fit test for normality could yield

Type I error but not Type II error.

Which statement is most nearly correct regarding ECDF tests?

When raw data are available, ECDF tests usually surpass the chi-square test in their ability to detect departures from the distribution specified in the null hypothesis.

Which of the following is correct?

When the sample size increases, β may decrease.

If a fitted trend equation is yt = 120 − 40t + 2.5t2, then the turning point will be

a trough in period 8.

A multivariate data set contains

more than two variables.

Refer to the following partial ANOVA results from Excel (some information is missing). ANOVA Table SourceSSdfMSFTreatment44,757 11,189 Error89,025551,619 Total133,78259 The p-value for the F-test would be

much less than .05.

For a given set of values for x1, x2, . . . , xk the confidence interval for the conditional mean of Y is

narrower than the prediction interval for the individual Y value.

Which is a time series variable?

net earnings reported by Xena Corporation for the last 10 quarters

Variation "within" the ANOVA treatments represents

random variation.

Which is not an analytical method commonly used to improve business decisions?

reactive analytics

Measurements from a sample are called

statistics

A population has groups that have a small amount of variation within them, but large variation among or between the groups themselves. The proper sampling technique is

stratified

Which is not a goal of the ethical data analyst?

to learn to downplay inconvenient data

We would use a logistic regression model

to predict an event that occurs or does not occur.

Which is not an ethical obligation of a statistician?

to support client wishes in drawing conclusions from the data

In a statistical test, we

try to reject the null hypothesis.

In a one-factor ANOVA, the computed value of F will be negative

under no circumstances.

Prediction intervals for Y are narrowest when

the value of X is near the mean of X.

If n = 25 and α = .05 in a right-tailed test of a mean with unknown σ, the critical value is

1.711.

A machine dispenses water into a glass. Assuming that the amount of water dispensed follows a continuous uniform distribution from 10 ounces to 16 ounces, the standard deviation of the amount of water dispensed is about

1.73 ounces.

The figure shows a normal N(400,23) distribution. Find the x value for the shaded area.

362.2

A local trucking company fitted a regression to relate the travel time (days) of its shipments as a function of the distance traveled (miles). The fitted regression is Time = −7.126 + .0214 Distance, based on a sample of 20 shipments. The estimated standard error of the slope is 0.0053. Find the critical value for a right-tailed test to see if the slope is positive, using α = .05.

1.734

Two well-known aviation training schools are being compared using random samples of their graduates. It is found that 70 of 140 graduates of Fly-More Academy passed their FAA exams on the first try, compared with 104 of 260 graduates of Blue Yonder Institute. The test statistic to test the pass rates for equality is

1.924.

The table below shows the mean number of daily errors by seven air traffic controller trainees during the first two weeks on the job. We want to perform a paired t-test at α = .05 to see if the mean daily errors have decreased from Week 1 to Week 2. Trainee T1T2T3T4T5T6T7Week 15.13.012.16.211.57.82.2Week 23.22.28.77.79.47.83.1 The right-tailed critical value at α = .05 is

1.943.

A test is conducted in 22 cities to see if giving away free transit system maps will increase the number of bus riders. In a regression analysis, the dependent variable Y is the increase in bus riders (in thousands of persons) from the start of the test until its conclusion. The independent variables are X1 = the number (in thousands) of free maps distributed and a binary variable X2 = 1 if the city has free downtown parking, 0 otherwise. The estimated regression equation is Y = 1.32 + 0.0345X1 − 1.45X2 . In city 3, the observed Y value is 7.3, X1 = 140, and X2 = 0. The residual for city 3 (in thousands) is

1.15

If arrivals follow a Poisson distribution with mean 1.2 arrivals per minute, find the 75th percentile of waiting times until the next arrival (i.e., 75 percent below).

1.155 minutes (69.3 seconds).

In a right-tailed test comparing two means with known variances, the sample sizes were n1 = 8 and n2 = 12. At α = .05, the critical value would be

1.645.

A psychology researcher has a theory that predicts women will tend to carry more cash than men. A random sample of Ersatz University students revealed that 16 females had a mean of $22.30 in their wallets with a standard deviation of $3.20, while 16 males had a mean of $17.30 with a standard deviation of $9.60. The test statistic for the researcher's hypothesis is

1.976.

How many ways can we choose three items at random without replacement from five items (A, B, C, D, E) if the order of the selected items is not important?

The value of 4P2 is

A company employs 300 employees. Each year, there is a 30 percent turnover rate for employees. We want to do a normal approximation to the binomial distribution of the number of employees who leave each year. For this normal approximation, the mean is __________ and the standard deviation is __________.

90, 7.937

TotCo is developing a new deluxe baby bassinet. If the length of a newborn baby is normally distributed with a mean of 50 centimeter and a standard deviation of 5 centimeter, what should be the interior length of the bassinet to ensure that 99 percent of newborn babies will fit, with a safety margin of 15 centimeter on each end of the bassinet?

91.63 centimeter.

Which of the following is not a valid description of an outlier?

A data value that lies below Q1 or above Q3.

Which of the following is not true about a discrete probability distribution

A discrete probability distribution can have probabilities that sum to more than 1.

A realtor is trying to predict the selling price of houses in Greenville (in thousands of dollars) as a function of Size (measured in thousands of square feet) and whether or not there is a fireplace (FP is 0 if there is no fireplace, 1 if there is a fireplace). Part of the regression output is provided below, based on a sample of 20 homes. Some of the information has been omitted. VariableCoefficientsStandard Errort-StatisticP-valueIntercept128.937462.620530249.2038.93E-20Size 1.207243611.4392.09E-09FP6.476019541.98036123.270.004512 Which statement is supported by the regression output?

A fireplace adds around $6,476 to the selling price of the average house.

Which of the following statements is not correct?

A statistical test result that is significant also has practical importance.

The 25th percentile for waiting time in a doctor's office is 19 minutes. The 75th percentile is 31 minutes. Which is incorrect regarding the fences?

A waiting time of 45 minutes exceeds the upper inner fence.

Which is not a characteristic of an effective summary table?

Data to be compared should be displayed in rows, not columns.

Which of the following statements is not true?

Estimating parameters is an important aspect of descriptive statistics.

Which of the following statements is not true?

For day-to-day business data analysis, most firms rely on a large staff of expert statisticians.

Which is a valid null hypothesis?

H0: μ = 18

Which of the following is not a valid null hypothesis?

H0: μ ≠ 0

Which is an invalid alternative hypothesis?

H1: μ = 18

Which probability model would you use to describe the number of damaged printers in a random sample of 4 printers taken from a shipment of 28 printers that contains 3 damaged printers?

Hypergeometric.

Which of the following is not a characteristic of the t distribution?

It approaches z as degrees of freedom decrease.

To measure satisfaction with its cell phone service, AT&T takes a stratified sample of its customers by age and location. Which is an advantage of this type of sampling, as opposed to other sampling methods?

It can give more accurate results.

The midhinge lies halfway between

Q1 and Q3.

Which statement is most nearly correct, other things being equal?

Quadrupling the sample size roughly halves the standard error of the mean.

Which of the following measures of fit is unit free?

R2 (coefficient of determination)

Which of the following is the sample space describing the number of cracked eggs in a full dozen carton?

S = {0, 1, 2, 3, ..., 11, 12}.

Which of the following is the sample space describing the number of items ordered at a McDonald's drive-thru?

S = {1, 2, 3, ...}.

Which statement is correct?

Selecting every fifth shopper arriving at a store will approximate a random sample of shoppers.

The ScamMore Energy Company is attempting to predict natural gas consumption for the month of January. A random sample of 50 homes was used to fit a regression of gas usage (in CCF) using as predictors Temperature = the thermostat setting (degrees Fahrenheit) and Occupants = the number of household occupants. They obtained the following results: VariableCoefficientStandard ErrorIntercept21.6844.122Temperature0.91420.2918Occupants2.2441.315 In testing each coefficient for a significant difference from zero (two-tailed test at α = .10), which is the most reasonable conclusion about the predictors?

Temperature is highly significant; Occupants is barely significant.

Bob thinks there is something wrong with Excel's fitted regression. What do you say?

The estimated equation is obviously incorrect.

Which statement is most nearly correct regarding time-series trend models?

The exponential model would be linear if we take the natural log of yt.

Refer to the following correlation matrix that was part of a regression analysis. The dependent variable was Abort (the number of abortions per 1000 women of childbearing age). The regression was estimated using data for the 50 U.S. states with these predictors: EdSpend = public K − 12 school expenditure per capita, Age = median age of population, Unmar = percent of total births by unmarried women, Infmor = infant mortality rate in deaths per 1000 live births. Correlation Matrix AbortEdSpendAgeUnmarInfMorAbort1.0000 EdSpend0.26261.0000 Age0.1610−0.04201.0000 Unmar0.3286−0.09490.09371.0000 InfMor−0.2513−0.28260.03890.52391.0000 Using a two-tailed correlation test, which statement is not accurate

The first column of the table shows evidence of multicollinearity.

The boxplot shows the spending for a sample of 50 breakfast customers of McDonald's. Which statement is least likely to be correct?

The mean is a reasonable measure of center.

Exam scores in a small class were 0, 50, 50, 70, 70, 80, 90, 90, 100, 100. For this data set, which statement is incorrect concerning measures of center?

The median is 70.

Exam scores in a random sample of students were 0, 50, 50, 70, 70, 80, 90, 90, 90, 100. Which statement is incorrect?

The midrange and mean are almost the same.

Regarding continuous probability distributions, which statement is incorrect?

The normal distribution is sometimes skewed.

Regarding the rules of probability, which of the following statements is correct?

The probability of A or its complement equals one.

Which best exemplifies the empirical definition of probability?

The probability that a checked bag on Flight 1872 will weigh less than 30 pounds.

Which best exemplifies a subjective probability?

The probability that the summer Olympic games will be held in Chicago in 2028.

Which is not a discrete random variable?

The time until failure of a vehicle headlamp.

Do variables X and Y have the same correlation in both scatter plots?

Their correlations are similar in magnitude but opposite in direction.

Refer to this ANOVA table from a regression: SourcedfSSMSFRegression41793.2356448.30897.48540Residual452695.099659.8911 Total494488.3352 Which statement is not accurate?

There were 5 predictors.

Craig operates a part-time snow-plowing business using a 2002 GMC 2500 HD extended cab short box truck. This box plot of Craig's MPG on 195 tanks of gas does not support which statement?

This is a very right-skewed distribution.

In a test of a new surgical procedure, the five most respected surgeons in FlatBroke Township were invited to Carver Hospital. Each surgeon was assigned two patients of the same age, gender, and overall health. One patient was operated upon in the old way, and the other in the new way. Both procedures are considered equally safe. The surgery times are shown below: Surgeon AllenBobChloeDaphneEdgarOld way3655284062New way3145283557 Which test should we use to test for zero difference in mean times?

Use the paired t-test.

Debbie has two stocks, X and Y. Consider the following events:X = the event that the price of stock X has increasedY = the event that the price of stock Y has increasedThe event "the price of stock X has increased and the price of stock Y has not increased" may be written as

X ∩ Y ′

If X2 is a binary predictor in Y = β0 + β1X1 + β2X2, then which statement is most nearly correct?

X2 will shift the estimated equation either by 0 units or by β2 units.

Of 200 youthful gamers (under 18) who tried the new Z-Box-Plus game, 160 rated it "excellent," compared with only 144 of 200 adult gamers (18 or over). Calculate the 95 percent confidence interval for the difference of proportions.

[−.003, +.163]

If the sample proportions were p1 = 12/50 and p2 = 18/50, what is the approximate 95 percent confidence interval for the difference of the population proportions?

[−.298, +.058]

The probability that event A occurs, given that event B has occurred, is an example of:

a conditional probability.

The fitted sales trend over the last 12 years is yt = 14.7e0.063t. We can say that

a continuously compounded model was used.

Which of the following is the least useful time-series forecasting model when there is a strong upward trend in the data?

a five-period centered moving average

Histograms are best used to

assess the shape of the distribution.

To test the null hypothesis H0: μ1 = μ2 = μ3 using samples from normal populations with unknown but equal variances, we

can safely employ ANOVA.

Which is least likely to be an application where statistics will be useful?

choosing the wording of a corporate policy prohibiting smoking

Which is not a time series variable?

closing checkbook balances of 30 students on December 31 of this year

An advantage of convenience samples over random samples is that

data collection cost is reduced.

As the sample size increases, the standard error of the mean

decreases.

Variation "between" the ANOVA treatments represents

differences between group means.

A stratified sample is sometimes recommended when

distinguishable strata can be identified in the populations.

Professor Gristmill sampled exam scores for five randomly chosen students from each of his two sections of ACC 200. His sample results are shown. Day Class9358748582Night Class9181856073 He could test the population means for equality using

either a one-factor ANOVA or a two-tailed t-test.

Which is not an assumption of ANOVA?

equal population sizes for groups

Analysis of variance is a technique used to test for

equality of two or more means.

We would associate the term inferential statistics with which task?

estimating unknown parameters

Histograms generally do not reveal the

exact data range.

An open-ended bin (e.g., "50 and over") might be seen in a frequency distribution when

extremely large data values exist.

The fitted annual sales trend is Yt = 187.3e−.047t. On average, sales are

falling by a declining absolute amount each year.

To carry out a chi-square goodness-of-fit test for normality you need at least

five expected observations in each category.

A contingency table shows

frequency counts.

A reliable survey is one that

gives consistent measurements.

Which is not an essential characteristic of a good business data analyst?

has a Ph.D. or Master's degree in statistics

The values of xmin and xmax can be inferred accurately except in a

histogram

A comparison of hours worked per week by randomly chosen Russian and Japanese men is shown below. Which test would be preferred to compare the means? RussianJapaneseSample mean50.0653.06Sample Standard Deviation2.4355.422Sample Size 1616

independent sample t-test for difference of two means assuming unequal variances

Which type of data could be used to calculate an average?

interval

Fluctuations caused by strikes and floods are

irregular fluctuations.

The time-series model Y = T × C × S × I

is a multiplicative model.

In the model yt = 516 − 42t + 3t2 the turning point

is a trough.

The standard error of the regression

is based on squared deviations from the regression line.

The critical value in a hypothesis test

is determined by α and the type of test.

The F-test for equality of variances assumes

normal populations.

A good data analyst

reports findings that may contradict client's ideas.

In testing the hypotheses H0: π ≤ π0, H1: π > π0, we would use a

right-tailed test.

Which is a categorical variable?

the brand of jeans you usually wear

The level of significance is not

the chance of failing to reject a true null hypothesis.

A logistic regression is appropriate when

the dependent variable is binary (0, 1).

The Central Limit Theorem implies that

the distribution of the mean is approximately normal for large n.

Which of the following is numerical data?

the fuel economy (MPG) of your car

William used a sample of 68 large U.S. cities to estimate the relationship between Crime (annual property crimes per 100,000 persons) and Income (median annual income per capita, in dollars). His estimated regression equation was Crime = 428 + 0.050 Income. We can conclude that

the intercept is irrelevant because zero median income makes no sense.

The critical value in a chi-square test for independence depends on

the number of categories.

Which is a discrete variable?

the number of pairs of jeans that you own

The geometric distribution best describes

the number of trials until the first success.

When comparing the 90 percent prediction and confidence intervals for a given regression analysis

the prediction interval is wider than the confidence interval.

The necessary sample size does not depend on

the type of sampling method used.

Here is an Excel ANOVA table that summarizes the results of an experiment to assess the effects of ambient noise level and plant location on worker productivity. The test used α = .05. Source of VariationSSdfMSFP-valueF critPlant location3.007531.00252.5610.11993.862Noise level8.407532.80257.1600.00933.863Error3.522590.3914 Total14.9375 The experimental design and ANOVA appear to be

unreplicated two-factor.

"Circulation fell in the month after the new editor took over the newspaper Oxnard News Herald. The new editor should be fired." Which is not a serious fallacy in this conclusion?

using a biased sample

We could narrow a 95 percent confidence interval by

using a larger sample.

The process that produces Sonora Bars (a type of candy) is intended to produce bars with a mean weight of 56 gram. The process standard deviation is known to be 0.77 gram. A random sample of 49 candy bars yields a mean weight of 55.82 gram. Find the test statistic to see whether the candy bars are smaller than they are supposed to be.

−1.636

If a fitted trend equation is yt = 120 − 40t + 2.5t2, then the forecast for period 5 will be

−17.5.

Which best illustrates the distinction between statistical significance and practical importance?

"Our new manufacturing technique has increased the life of the 80 GB USB AsimoDrive external hard disk significantly, from 240,000 hours to 250,000 hours."

A fair die is rolled. If it comes up 1 or 2 you win $2. If it comes up 3, 4, 5, or 6, you lose $1. Calculate the expected winnings.

$0.00

A computer analysis reveals that the best-fitting trend model is yt = 4.12e0.987t. The trend was fitted using year-end common stock prices for Melodic Kortholt Outlet for the last six years. The R2 is .8571. What is the forecast for year seven's stock price?

$4125

The owner of Torpid Oaks B&B wanted to know the average distance its guests had traveled. A random sample of 16 guests showed a mean distance of 85 miles with a standard deviation of 32 miles. The 90 percent confidence interval (in miles) for the mean is approximately

(71.0, 99.0)

Using a sample of 63 observations, a dependent variable Y is regressed against two variables X1 and X2 to obtain the fitted regression equation Y = 76.40 − 6.388X1 + 0.870X2. The standard error of b1 is 3.453 and the standard error of b2 is 0.611. tcalc for β2 =

+1.424.

Given the contingency table shown here, find P(V | S). Vehicle TypeSomerset (S)Oakland (O)Great Lakes (G)Row TotalCar (C)444936129Minivan (M)21151854Full-Size Van (F)2338SUV (V)19272672Truck (T)1461737Col Total100100100300

,1900

A fitted regression Profit = −570 + 30 Sales (all variables in thousands of dollars) was estimated from a random sample of 20 pharmacies. For a pharmacy with Sales = 10, we predict that Profit will be

-270

On average, a major earthquake (Richter scale 6.0 or above) occurs 3 times a decade in a certain California county. What is the probability that less than six months will pass before the next earthquake?

.1393

Given the contingency table shown here, find P(E | F). MajorGenderAccounting (A)General Management (G)Economics (E)Row TotalMale (M)210180140530Female (F)150160160470Col Total3603403001000

.340

Given the contingency table shown here, find P(A1 or B2).

.3854

Refer to this ANOVA table from a regression: SourcedfSSMSFRegression41793.2356448.30897.48540Residual452695.099659.8911 Total494488.3352 For this regression, the R2 is

.3995.

Given the contingency table shown here, find the probability that either event A2 or event B2 will occur.

.4454

At Dolon General Hospital, 30 percent of the patients have Medicare insurance (M) while 70 percent do not have Medicare insurance (M´). Twenty percent of the Medicare patients arrive by ambulance, compared with 10 percent of the non-Medicare patients. If a patient arrives by ambulance, what is the probability that the patient has Medicare insurance?

.4615

Professor York randomly surveyed 240 students at Oxnard University and found that 150 of the students surveyed watch more than 10 hours of television weekly. Develop a 95 percent confidence interval to estimate the true proportion of students who watch more than 10 hours of television each week. The confidence interval is

.564 to .686

Given the contingency table shown here, find P(W | M).Survey question: Do you plan on retiring or keep working when you turn 65?

.581

If X is a discrete uniform random variable ranging from one to eight, find P(X < 6).

.6250

Find the probability that either event A or B occurs if the chance of A occurring is .5, the chance of B occurring is .3, and events A and B are independent.

.65

When you send out a resume, the probability of being called for an interview is .20. What is the probability that you get your first interview within the first five resumes that you send out?

.6723

The discrete random variable X is the number of students that show up for Professor Smith's office hours on Monday afternoons. The table below shows the probability distribution for X. What is the probability that fewer than 2 students come to office hours on any given Monday? X0123TotalP(X).40.30.20.101.00

.70

An insurance company is issuing 16 car insurance policies. Suppose the probability for a claim during a year is 15 percent. If the binomial probability distribution is applicable, then the probability that there will be at least two claims during the year is equal to

.7161

There are 90 passengers on a commuter flight from SFO to LAX, of whom 27 are traveling on business. In a random sample of five passengers, use the binomial model to find the approximate hypergeometric probability that there is at least one business passenger.

.8319

The probability that a rental car will be stolen is .0004. If 3500 cars are rented, what is the approximate Poisson probability that 2 or fewer will be stolen?

.8335

On average, 15 minutes elapse between discoveries of fraudulent corporate tax returns in a certain IRS office. What is the probability that less than 30 minutes will elapse before the next fraudulent corporate tax return is discovered?

.8647

Given the contingency table shown here, find P(L or W). Survey question: Do you plan on retiring or keep working when you turn 65? EmployeeRetire (R)Work (W)TotalManagement (M)131831Line worker (L)395493Total5272124

.895

The probability that a customer will use a stolen credit card to make a purchase at a certain Target store is .003. If 400 purchases are made in a given day, what is the approximate Poisson probability that 4 or fewer will be with stolen cards?

.9923

In Quebec, 90 percent of the population subscribes to the Roman Catholic religion. In a random sample of eight Quebecois, find the probability that the sample contains at least five Roman Catholics.

.9950

Last year, 10 percent of all teenagers purchased a new iPhone. This year, a sample of 260 randomly chosen teenagers showed that 39 had purchased a new iPhone. To test whether the percentage has risen, the p-value is approximately

0.0036.

In a random sample of patient records in Cutter Memorial Hospital, six-month postoperative exams were given in 90 out of 200 prostatectomy patients, while in Paymor Hospital such exams were given in 110 out of 200 cases. In a left-tailed test for equality of proportions, the p-value is

0.0228.

In a right-tailed test comparing two proportions, the test statistic was zcalc = +1.81. The p-value is

0.0351

A random sample of 160 commercial customers of PayMor Lumber revealed that 32 had paid their accounts within a month of billing. The 95 percent confidence interval for the true proportion of customers who pay within a month would be

0.138 to 0.262

The table below shows two samples taken to compare the mean age of individuals who purchased the iPhone at two AT&T store locations. StatisticAnn ArborLivoniaMean25.81731.248Standard Deviation3.3891.874Sample size710 What are the critical values for a two-tailed test for equal variances at α = .05?

0.181, 4.32

At Huge University, a sample of 200 business school seniors showed that 26 planned to pursue an MBA degree, compared with 120 of 800 arts and sciences seniors. We want to know if the proportion is higher in the arts and sciences group. The p-value for a left-tailed test is approximately

0.24.

Carver Memorial Hospital's surgeons have a new procedure that they think will decrease the variance in the time it takes to perform an appendectomy. A sample of 8 appendectomies using the old method had a variance of 36 minutes, while a sample of 10 appendectomies using the experimental method had a variance of 16 minutes. At α = .10 in a two-tailed test for equal variances, the critical values are

0.272 and 3.29.

Of 200 youthful gamers (under 18) who tried the new Z-Box-Plus game, 160 rated it "excellent," compared with only 144 of 200 adult gamers (18 or over). The pooled proportion for a test to compare the two proportions would be

0.76.

A new policy of "flex hours" is proposed. Random sampling showed that 28 of 50 female workers favored the change, while 22 of 50 male workers favored the change. Management wonders if there is a difference between the two groups. What is the test statistic to test for a zero difference in the population proportions?

1.200

The table below shows the mean number of daily errors by air traffic controller trainees during the first two weeks on the job. We want to perform a paired t-test at α = .05 to see if the mean daily errors decreased significantly. Trainee T1T2T3T4T5T6T7Week 15.13.012.16.211.57.82.2Week 23.22.28.77.79.47.83.1 The test statistic is

1.25

1.25.

For this one-factor ANOVA (some information is missing), what is the F-test statistic? SourceSum of SquaresdfMean SquareFTreatment654 218 Error3,456 128 Total4,110

1.703

If n = 15 and r = .4296, the corresponding t statistic to test for zero correlation is

1.715.

Ten percent of the corporate managers at Axolotl Industries majored in humanities. What is the expected number of managers to be interviewed before finding the first one with a humanities major?

To compare the cost of three shipping methods, a firm ships material to each of four different destinations over a six-month period. The average cost per shipment is shown below. DestinationShipperToledoOshawaJanesvilleDallasSpeedyShip355435422518GetItThere342441402488WeRTops361430435528 For the appropriate type of ANOVA, total degrees of freedom would be

An operations analyst counted the number of arrivals per minute at an ATM in each of 30 randomly chosen minutes. The results were: 0, 3, 3, 2, 1, 0, 1, 0, 0, 1, 1, 1, 2, 1, 0, 1, 0, 1, 2, 1, 1, 2, 1, 0, 1, 2, 0, 1, 0, 1. For the Poisson goodness-of-fit test, what is the expected frequency of the data value X = 1?

11.04

Refer to the following partial ANOVA results from Excel (some information is missing). Source of VariationSSdfMSFNozzle setting3.4672213.467224.87198Pressure level8.07444 4.037225.67291Interaction2.8077921.403891.97268Error8.54000 0.711667 Total22.8894 Error degrees of freedom would be

If a fitted trend equation is yt = 816e0.065t, which is the forecast for period 7?

1286

A realtor is trying to predict the selling price of houses in Greenville (in thousands of dollars) as a function of Size (measured in thousands of square feet) and whether or not there is a fireplace (FP is 0 if there is no fireplace, 1 if there is a fireplace). Part of the regression output is provided below, based on a sample of 20 homes. Some of the information has been omitted. VariableCoefficientsStandard Errort-StatisticIntercept128.937462.620530249.203Size 1.207243611.439FP6.476019541.98036123.27 The estimated coefficient for Size is approximately

13.8

Systolic blood pressure of randomly selected HMO patients was recorded on a particular Wednesday, with the results shown here. An ANOVA test was performed using these data. Patient Age GroupUnder 2020 to 2930 to 4950 and Over105110122139113101114115108112128136114127124124123123125123 What are the degrees of freedom for the error sum of squares?

Last week, 108 cars received parking violations in the main university parking lot. Of these, 27 had unpaid parking tickets from a previous violation. Assuming that last week was a random sample of all parking violators, find the 95 percent confidence interval for the percentage of parking violators that have prior unpaid parking tickets.

16.8 to 33.2 percent.

If X is a discrete uniform random variable ranging from 12 to 24, what is its mean?

18.0

As an independent project, a team of statistics students tabulated the types of vehicles that were parked in four different suburban shopping malls. Mall LocationVehicle TypeSomersetOaklandGreat LakesJamestownRow TotalCar44493664193Minivan2115181367Full-size Van233210SUV1927261284Truck14617946Column Total100100100100400 For a chi-square test of independence, the critical value for α = .10 is

18.55

A veterinarian notes the age (months) at which dogs are brought in to the clinic to be neutered. ColliesTerriesChowsMale10148 91018 12811Female15179 71115 868 Numerator degrees of freedom for the ANOVA interaction test would be

The Internal Revenue Service wishes to study the time required to process tax returns in three regional centers. A random sample of three tax returns is chosen from each of three centers. The time (in days) required to process each return is recorded as shown below. EastWestMidwest494754395249455156 Degrees of freedom for the between-groups sum of squares in the ANOVA would be

2 × 3 table.

Guidelines for the Jolly Blue Giant Health Insurance Company say that the average hospitalization for a triple hernia operation should not exceed 30 hours. A diligent auditor studied records of 16 randomly chosen triple hernia operations at Hackmore Hospital and found a mean hospital stay of 40 hours with a standard deviation of 20 hours. "Aha!" she cried, "the average stay exceeds the guideline." The value of the test statistic for her hypothesis is

2.000.

Guidelines for the Jolly Blue Giant Health Insurance Company say that the average hospitalization for a triple hernia operation should not exceed 30 hours. A diligent auditor studied records of 16 randomly chosen triple hernia operations at Hackmore Hospital and found a mean hospital stay of 40 hours with a standard deviation of 20 hours. "Aha!" she cried, "the average stay exceeds the guideline." At α = .025, the critical value for a right-tailed test of her hypothesis is

2.131

John wants to compare two means. His sample statistics were x⎯⎯x¯ 1 = 22.7, s12 = 5.4, n1 = 9 and x⎯⎯x¯ 2 = 20.5, s22 = 3.6, n2 = 9. Assuming equal variances, the test statistic is

2.20.

In a multiple regression with six predictors in a sample of 67 U.S. cities, what would be the critical value for an F test of overall significance at α = .05?

2.25

A multinational firm manufactures several types of 1280 × 1024 LCD displays in several locations. They designed a sampling experiment to analyze the number of pixels per screen that have significant color degradation after 52,560 hours (six years of continuous use) using accelerated life testing. The Excel ANOVA table for their experiment is shown below. Some table entries have been obscured. The response variable (Y) is the number of degraded pixels in a given display. Source of VariationSSdfMSFP-valueF critCountry of origin202.9 101.454.1634750.021927 Display type233.2333 58.30833 Interaction147.7667 18.47084 Error1096.54524.36667 Total1680.459 The F statistic for display effect is

2.39

In a multiple regression with five predictors in a sample of 56 U.S. cities, what would be the critical value for an F test of overall significance at α = .05?

2.4

A sample of 16 ATM transactions shows a mean transaction time of 67 seconds with a standard deviation of 12 seconds. Find the critical value to test whether the mean transaction time exceeds 60 seconds at α = .01.

2.602

Last year, 10 percent of all teenagers purchased a new iPhone. This year, a sample of 260 randomly chosen teenagers showed that 39 had purchased a new iPhone. The test statistic to find out whether the percentage has risen would be

2.687.

The researcher's null hypotheses is H0: σ2 = 420. A sample of n = 18 items yields a sample variance of s2 = 512. The test statistic is

20.72.

A certain assembly line at Vexing Manufacturing Company averages 30 minutes between breakdowns. The median time between breakdowns is

20.8 minutes.

Given the following probability distribution with E(X) = 200, what is the variance of the random variable X? XP(X)100.10200.80300.10

2000

Given the following probability distribution, what is the expected value of the random variable X? XP(X)100.10150.20200.30250.30300.10Sum1.00

205

If Y1 = 116 and Y7 = 255, which is the simple index number for period 7 (denoted I7)?

219.8Correct

You want to test the hypothesis that the prime rate and inflation are independent. The following table is prepared for the test on the basis of the results of a random sample, collected in various countries and various time periods shown below. Prime RateInflation Rates6-February10-July20-NovemberRow TotalUnder 5%40305755% or more5304075Column Total456045150 The expected frequency for the cell in row 2 and column 3 is

22.5

The Excel function =800*RAND() would generate random numbers with standard deviation approximately equal to

231

Refer to the following partial ANOVA results from Excel (some information is missing). ANOVA Table SourceSSdfMSFP-valueTreatment717.43 .0442Error 70.675 Total1848.219 The MS (mean square) for the treatments is

239.13.

Given the following probability distribution with E(X) = 200, what is the variance of the random variable X? XP(X)100.70300.10500.20

26,000

In Melanie's Styling Salon, the time to complete a simple haircut is normally distributed with a mean of 25 minutes and a standard deviation of 4 minutes. The slowest quartile of customers will require more than how many minutes for a simple haircut?

27.7 minutes.

During a test period, an experimental group of 10 vehicles using an 85 percent ethanol-gasoline mixture showed mean CO2 emissions of 667 pounds per 1000 miles, with a standard deviation of 20 pounds. A control group of 14 vehicles using regular gasoline showed mean CO2 emissions of 679 pounds per 1000 miles with a standard deviation of 15 pounds. Assuming equal variances, the pooled variance is

296.59.

A firm is concerned with variability in hourly output at several factories and shifts. Here are the results of an ANOVA using output per hour as the dependent variable (some information is missing). SourceSum of SquaresdfMean SquareF RatioFactory19012.5119012.526.427Supplier258.3332129.1670.180Factory*Shift80908.333240454.16756.230Error8633.33312719.444 Total108812.5176400.735 The number of observations in each treatment cell (row-column intersection) is

Degrees of freedom for the between-group variation in a one-factor ANOVA with n1 = 8, n2 = 5, n3 = 7, n4 = 9 would be

Oxnard Casualty wants to ensure that their e-mail server has 99.98 percent reliability. They will use several independent servers in parallel, each of which is 95 percent reliable. What is the smallest number of independent file servers that will accomplish the goal?

Refer to the following partial ANOVA results from Excel (some information is missing). Source of VariationSSdfMSFBetween groups 210.2778 Within groups1483 74.15 Total2113.833 Degrees of freedom for between-groups variation are

Sound engineers studied factors that might affect the output (in decibels) of a rock concert speaker system. The results of their ANOVA tests are shown (some information is missing). Source of VariationSSdfMSFAmplifier99.02344 99.02344 Position93.98698 31.328993.215807Interaction10.1536533.3845490.347412Error155.875169.742188 Total359.039123 The number of observations per cell was

Identify the degrees of freedom for the treatment and error in this one-factor ANOVA (blanks indicate missing information). SourceSum of SquaresdfMean SquareTreatment993 331.0Error1,002 50.1Total1,99523

3,20

The heights of male students in a certain statistics class range from Xmin = 61 to Xmax = 79. Applying the Empirical Rule, a reasonable estimate of σ would be

3.00

Given the following ANOVA table (some information is missing), find the critical value of F.05. SourceSum of SquaresdfMean SquareFF.05Treatment744.004 Error751.5015 Total1,495.5019

3.06

Given the following ANOVA table (some information is missing), find the critical value of F.05. SourceSum of SquaresdfMean SquareFF.05Treatment744.004 Error751.5015 Total1,495.5019

3.06

Based on a random sample of 13 tire changes, the mean time to change a tire on a Boeing 777 has a mean of 59.5 minutes with a standard deviation of 8.4 minutes. For 10 tire changes on a Boeing 787, the mean time was 64.3 minutes with a standard deviation of 12.4 minutes. To test for equal variances in a two-tailed test at α = .10, the critical values are

3.07 and 0.357.

Refer to the following partial ANOVA results from Excel (some information is missing). Source of VariationSSdfMSFP-valueF critBetween groups 210.2778 0.064139 Within groups1483 74.15 Total2113.833 The critical value of F at α = .05 is

3.10

Refer to the following partial ANOVA results from Excel (some information is missing). ANOVA table SourceSSdfMSFP-valueTreatment717.43 .0442Error 70.675 Total1848.219 The 5 percent critical value for the F test is

3.24

A hypothesis test is conducted at the 5 percent level of significance to test whether the population correlation is zero. If the sample consists of 25 observations and the correlation coefficient is .60, what is the computed test statistic?

3.597Correct

Given the following ANOVA table (some information is missing), find the F statistic. SourceSum of SquaresdfMean SquareFTreatment744.004 Error751.5015 Total1,495.5019

3.71

For a sample of size 11, the critical values of chi-square for a 90 percent confidence interval for the population variance are

3.940, 18.31

The researcher's null hypotheses is H0: σ2 ≤ 22. A sample of n = 25 items yields a sample variance of s2 = 28.5. The test statistic is

31.09.

Here is an Excel ANOVA table for an experiment that analyzed two factors that may affect patients' blood pressure (some information is missing). Source of VariationSSdfMSFP-valueMedication type16.5313116.53139.1730.006Patient age group25.0938 8.36464.6420.011Interaction1.843830.61460.3410.796Error43.2504241.8021 Total86.7192 The overall sample size is

For these data, what is the three-period trailing moving average for period 6? t123456789yt223327343826283541

32.67

For these data, what is the three-period centered moving average for period 4? t123456789yt223327343826283541

33.00

The researcher's null hypothesis is H0: σ2 ≤ 22. A sample of n = 25 items yields a sample variance of s2 = 28.5. The critical value of chi-square for a right-tailed test at α = .05 is

36.42.

For this one-factor ANOVA (some information is missing), how many treatment groups were there? SourceSum of SquaresdfMean SquareFTreatment654 218 Error3,456 128 Total4,110

The expected value of a random variable X is 10 and the standard deviation is 2. The standard deviation of the random variable Y = 2X − 10 is

A local trucking company fitted a regression to relate the travel time (days) of its shipments as a function of the distance traveled (miles). The fitted regression is Time = −7.126 + 0.0214 Distance, based on a sample of 20 shipments. The estimated standard error of the slope is 0.0053. Find the value of tcalc to test for zero slope.

4.04

A proofreader checked 160 ads for grammatical errors. The sample frequency distribution is shown below. Number of Errors0123Observed Frequency10657114 Under the null hypothesis of a uniform distribution, the expected number of times we would get 0 errors is

The coefficient of variation for a Poisson distribution with λ = 5 is

44.7 percent.

The time required for a citizen to complete the 2020 U.S. Census "long" form is normally distributed with a mean of 40 minutes and a standard deviation of 10 minutes. What is the third quartile (in minutes) for the time required to complete the form?

46.75

A multinational firm manufactures several types of 1280 × 1024 LCD displays in several locations. They designed a sampling experiment to analyze the number of pixels per screen that have significant color degradation after 52,560 hours (six years of continuous use) using accelerated life testing. The Excel ANOVA table for their experiment is shown below. Some table entries have been obscured. The response variable (Y) is the number of degraded pixels in a given display. Source of VariationSSdfMSFCountry of origin202.9 101.454.163475Display type233.2333 58.30833 Interaction147.7667 18.47084 Error1096.54524.36667 Total1680.459 How many display types were there?

The Oxnard Retailers Anti-Theft Alliance (ORATA) published a study that claimed the causes of disappearance of inventory in retail stores were 30 percent shoplifting, 50 percent employee theft, and 20 percent faulty paperwork. The manager of the Melodic Kortholt Outlet performed an audit of the disappearance of 80 items and found the frequencies shown below. She would like to know if her store's experience follows the same pattern as other retailers. ReasonShopliftingEmployee TheftPoor PaperworkFrequency323810 The value of the chi-square test statistic you would use in testing whether there is a difference from the published pattern is

5.02

The Oxnard Retailers Anti-Theft Alliance (ORATA) published a study that claimed the causes of disappearance of inventory in retail stores were 30 percent shoplifting, 50 percent employee theft, and 20 percent faulty paperwork. The manager of the Melodic Kortholt Outlet performed an audit of the disappearance of 80 items and found the frequencies shown below. She would like to know if her store's experience follows the same pattern as other retailers. ReasonShopliftingEmployee TheftPoor PaperworkFrequency323810 Using α = .05, the critical value you would use in determining whether the Melodic Kortholt Outlet's pattern differs from the published study is

5.991

A taste test of randomly selected students was conducted to see if there was a difference in preferences among four popular drinks. The following table shows the frequency of responses. BeverageCokePepsiA&W Root BeerDr PepperFrequency51664340 The expected number of students preferring Dr. Pepper is

A project has three independent stages that must be completed in sequence. The time to complete each stage is a random variable. The expected times to complete the stages are μ1 = 23, μ2 = 11, μ3 = 17. The expected project completion time is

54.44

Based on the following regression ANOVA table, what is the MS for the residuals? SourcedfSSMSFRegression41793.2356448.30897.48540Residual452695.0996 Total494488.3352

59.8911

A firm is concerned with variability in hourly output at several factories and shifts. Here are the results of an ANOVA using output per hour as the dependent variable (some information is missing). SourceSum of SquaresdfMean SquareF RatioFactory19012.5119012.526.427Supplier258.3332129.1670.180Factory*Shift80908.333240454.16756.230Error8633.33312719.444 Total108812.5176400.735 The original data matrix has how many treatments (rows × columns)?

The Internal Revenue Service wishes to study the time required to process tax returns in three regional centers. A random sample of three tax returns is chosen from each of three centers. The time (in days) required to process each return is recorded as shown below. Subsequently, an ANOVA test was performed. EastWestMidwest494754395249455156 Degrees of freedom for the error sum of squares in the ANOVA would be

For a sample of size 16, the critical values of chi-square for a 95 percent confidence interval for the population variance are

6.262, 27.49

A random variable is binomially distributed with n = 16 and π = .40. The expected value and standard deviation of the variables are

6.40 and 1.96.

Estimate the mean exam score for the 50 students in Professor Axolotl's class.

62.0

Use the estimated regression equation yt = 448 + 12t + 18 Qtr1 − 26 Qtr2 + 3 Qtr3 to make a forecast for period 13. The regression model has three quarterly binaries (0 or 1). The model was fitted to 12 periods of quarterly data, starting with the first quarter.

622

Consider the following data: 6, 7, 17, 51, 3, 17, 23, and 69. The range and the median are

66 and 17.

A fitted regression for an exam in Prof. Hardtack's class showed Score = 20 + 7 Study, where Score is the student's exam score and Study is the student's study hours. The regression yielded R2 = 0.50 and SE = 8. Bob studied 9 hours. The quick 95 percent prediction interval for Bob's grade is approximately

67 to 99.

If the mean waiting time for the next arrival is 12 minutes, what is the median waiting time?

8.3 minutes.

A project has 3 independent stages that must be completed in sequence. The time to complete each stage is a random variable. The standard deviations of the completion times for the stages are σ1 = 5, σ2 = 4, σ3 = 6. The standard deviation of the overall project completion time is

8.77

A data set has 5,500 observations. When the data are represented in a relative frequency distribution, the relative frequency of a given interval is 0.15. The frequency in this interval is equal to

825.

Exam scores were normal in BIO 200. Jason's exam score was one standard deviation above the mean. What percentile is he in?

84th

Part of a regression output is provided below. Some of the information has been omitted. Source of variationSSdfMSFRegression3177.1721588.6 Residual 1717.717 Total3478.3619 The approximate value of F is

89.66.

If you have 256 data points, how many classes (bins) would Sturges' Rule suggest?

A random sample of Ersatz University students revealed that 16 females had a mean of $22.30 in their wallets with a standard deviation of $3.20, while 6 males had a mean of $17.30 with a standard deviation of $9.60. The value of the test statistic for a folded F-test for equal variances is

9.00

The table below is a tabulation of opinions of employees of Axolotl Corporation, who were sampled at random from pay records and asked to complete an anonymous job satisfaction survey, with the results shown below. Degree of SatisfactionPay TypeSatisfiedNeutralDissatisfiedRow TotalSalaried40101060Hourly805050180Column Total1206060240 Assuming independence, the expected frequency of satisfied hourly employees is

Which measure of is unit-free?

=CORREL(Xdata, YData)

Which Excel function would give a p-value for a left-tailed F test to compare two sample variances?

=F.DIST(s12/s22, df1,df2)

The estimated regression equation is yt = 448 + 12t + 18 Qtr1 − 26 Qtr2 + 3 Qtr3. The regression model has three quarterly binaries. The model was fitted to 12 periods of quarterly data starting with the first quarter. Why is there no fourth quarterly binary for Qtr4?

Because it is unnecessary. (Its value is implied by the other three binaries.)

Assume 30% of the population has a nut allergy. Which of the following distributions is most appropriate to describe the number of people in a sample of 42 who have a nut allergy?

Binomial

In a continuous distribution the

CDF is used to find left-tail probabilities.

The following table shows the number of credit cards owned by randomly chosen customers of Axolotl Bank. Which test would be preferred to compare the number of credit cards owned by individuals with only a checking account versus customer with both checking and savings accounts? Checking only0126101317225Both checking and saving8915

Difference of two means in independent samples.

For U.S. adult males, the mean height is 178 cm with a standard deviation of 8 cm and the mean weight is 84 kg with a standard deviation of 8 kg. Elmer is 170 cm tall and weighs 70 kg. It is most nearly correct to say that

Elmer's weight is more unusual than his height.

Which trend would you choose to forecast the 2013 value of Bob's beer can collection?

Exponential model is preferred.

Which probability model would you use to describe the number of customers served at a certain California Pizza Kitchen until the first customer orders split pea soup?

Geometric

Which statement is incorrect?

If there is a binary predictor (X = 0, 1) in the model, the residuals may not sum to zero.

A fitted multiple regression equation is Y = 28 + 5X1 − 4X2 + 7X3 + 2X4. When X1 increases 2 units and X2 increases 2 units as well, while X3 and X4 remain unchanged, what change would you expect in your estimate of Y?

Increase by 2.

Which is a reason for using a log scale for time series data?

It helps compare growth in time series of dissimilar magnitude.

Which is a characteristic of the variance inflation factor (VIF)?

It indicates the predictor's degree of multicollinearity.

Which is not true of the two-tailed F-test for equality of variances?

It is fairly robust to the presence of nonnormality in the populations being sampled.

Which is not true of the coefficient of determination?

It is negative when there is an inverse relationship between X and Y.

Which is true of the kurtosis of a distribution?

It is risky to assess kurtosis if the sample size is less than 50.

Which is not correct regarding the estimated slope of the OLS regression line?

It may be regarded as zero if its p-value is less than α.

Which of the following is not true of the standard error of the regression?

It would be negative when there is an inverse relationship in the model.

Which of the following is true?

Line charts are not used for cross-sectional data.

Could this function be a PDF?

The relationship of Y to four other variables was established as Y = 12 + 3X1 − 5X2 + 7X3 + 2X4. When X1 increases 5 units and X2 increases 3 units, while X3 and X4 remain unchanged, what change would you expect in your estimate of Y?

No change.

Which is correct concerning a two-factor unreplicated (randomized block) ANOVA?

No interaction effect is estimated.

Mary did an analysis of variances in samples of acute care occupancy rates at two community hospitals and obtained the following results: F-test for equality of variancevariance: group 1108.243variance: group 198.371F1.100p-value0.905 Can Mary conclude that the variances are unequal at α = .05?

No, there is not enough evidence to believe the variances are unequal.

In the following regression (n = 91), which coefficients differ from zero in a two-tailed test at α = .05? Confidence IntervalVariablesCoefficients95% lower95% upperIntercept9.8080−23.996843.6129NumCyl−1.6804−2.8260−0.5349HPMax−0.0369−0.0648−0.0090ManTran0.2868−2.26042.8341Length0.1109−0.00870.2305Wheelbase−0.0701−0.41110.2709Width0.4079−0.17350.9893RearStRm−0.0085−0.41000.3931Weight−0.0025−0.00640.0014Domestic−1.2291−3.49551.0374

NumCyl, HPMax

In the following regression, which are the three best predictors? VariablesCoefficientsStandard Errort (df = 81)p-valueIntercept9.808016.99000.577.5654NumCyl−1.68040.5757−2.919.0045HPMax−0.03690.0140−2.630.0102ManTran0.28681.28020.224.8233Length0.11090.06011.845.0686Wheelbase−0.07010.1714−0.409.6836Width0.40790.29221.396.1665RearStRm−0.00850.2018−0.042.9666Weight−0.00250.0020−1.266.2090Domestic−1.22911.1391−1.079.2838

NumCyl, HPMax, Length

The number of people injured in rafting expeditions on the Colorado River on a randomly chosen Thursday in August is best described by which model?

Poisson

In a randomly chosen week, which probability model would you use to describe the number of accidents at the intersection of two streets?

Poisson.

Regarding the probability of Type I error (α) and Type II error (β), which statement is true?

Power = 1 − β.

Which of the following measures of fit is expressed in the same units as yt?

SE (standard error)

Which is correct to find the value of the coefficient of determination (R2)?

SSR/SST

Based on these regression results, in your judgment which statement is most nearly correct (Y = highway miles per gallon in 91 cars)? R20.499 Adjusted R20.444n91R0.707k9Standard Error4.019Dependent VariableHwyMPG SourceSSdfMSFp-valueRegression1,305.72519145.08068.98.0000Residual1,308.38488116.1529 Total2,614.109990

Some predictors are not contributing much.

The first column of the table shows evidence of multicollinearity.

Which statement is incorrect?

The hypergeometric distribution is always symmetric.

Which statement is correct for a simple index number?

The simple relative index for period t = 5 is calculated as Y5/Y1.

On the last exam in FIN 417, "Capital Budgeting Strategies" Bob's z-score was −1.15. Bob said, "Yipe! My score is within the bottom quartile." Assuming a normal distribution, is Bob right?

Yes

Does the Speedo Fastskin II Male Hi-Neck Bodyskin competition racing swimsuit improve a swimmer's 200-yard individual medley performance times? A test of 100 randomly chosen male varsity swimmers at several different universities showed that 66 enjoyed improved times, compared with only 54 of 100 female varsity swimmers. In comparing the proportions of males versus females, is it safe to assume normality?

Yes, clearly.

The table below shows two samples taken to compare the mean age of individuals who purchased the iPhone at two AT&T store locations. StatisticAnn ArborLivoniaMean25.81731.248Standard Deviation3.3891.874Sample size710 At α = .05, can you conclude that the first sample has a larger variance than the second sample?

Yes, the p-value < .05.

A section of the population we have targeted for analysis is

a frame.

The hypotheses H0: π ≥ .40, H1: π < .40 would require

a left-tailed test.

An observation in a data set would refer to

a single row that contains one or more observed variables.

A sampling distribution describes the distribution of

a statistic.

In constructing a 95 percent confidence interval, if you increase n to 4n, the width of your confidence interval will be (assuming other things remain the same)

about 50 percent of its former width.

Which of the following is not a characteristic of an ideal statistician?

always agrees with client's conclusions

A column chart would be least suitable to display which data?

annual compensation of 500 company CEOs

Of the following, the one that most resembles a Poisson random variable is the number of

annual power failures at your residence.

Chebyshev's Theorem

applies to all samples.

The Central Limit Theorem (CLT)

applies to any population.

You want to sell your house, and you decide to obtain an appraisal on it. Looking at past data, you discover that actual prices obtained for houses and the appraisals given for them prior to their sale were as shown below. Actual Selling PriceAppraisalUp to $500,000$500,001 or moreRow TotalUp to $500,00021930$500,001 or more14620Column Total351550 Based on these data we can say that

appraisal and actual price are independent at any α.

In order to apply the chi-square test of independence, we must have

at least five expected observations in each cell.

In a left-tailed test comparing two means with unknown variances assumed to be equal, the test statistic was t = −1.81 with sample sizes of n1 = 8 and n2 = 12. The p-value would be

between .025 and .05.

For a right-tailed test of a hypothesis for a population mean with n = 14, the value of the test statistic was t = 1.863. The p-value is

between .05 and .025.

The point halfway between the bin limits in a frequency distribution is known as the

bin midpoint.

Which is not a standard criterion for assessing the usefulness of a regression model?

binary predictors

In a sample of n = 40, a sample correlation of r = .400 provides sufficient evidence to conclude that the population correlation coefficient exceeds zero in a right-tailed test at

both α = .025 and α = .05.

A trend line has been fitted to a company's annual sales. The trend is given by yt = 50 + 5t, where t is the time index (t = 1, 2, . . . , n) and yt is annual sales (in millions of dollars). The implication of this trend line is that sales are expected to increase

by an average of $5 million per year.

Sampling error can be avoided

by no method under the statistician's control.

A new policy of "flex hours" is proposed. Random sampling showed that 28 of 50 female workers favored the change, while 22 of 50 male workers favored the change. Management wonders if there is a difference between the two groups. For a test comparing the two proportions, the assumption of normality for the difference of proportions is

clearly justified.

Two well-known aviation training schools are being compared using random samples of their graduates. It is found that 70 of 140 graduates of Fly-More Academy passed their FAA exams on the first try, compared with 104 of 260 graduates of Blue Yonder Institute. To compare the two proportions, the assumption of normality of the test statistic is

clearly justified.

The Centers for Disease Control and Prevention (CDC) wants to estimate the average extra hospital stay that occurs when heart surgery patients experience postoperative atrial fibrillation. They divide the United States into nine regions. In each region, hospitals are selected at random within each hospital size group (small, medium, large). In each hospital, heart surgery patients are sampled according to known percentages by age group (under 50, 50 to 64, 65 and over) and gender (male, female). This procedure combines which sampling methods?

cluster, stratified, and simple random

A histogram can be defined as a chart whose

column widths show class intervals and whose heights indicate frequencies.

Given H0: μ ≥ 18 and H1: μ < 18, we would commit a Type I error if we

conclude that μ < 18 when the truth is that μ ≥ 18.

A marketing professor wants to know how many MBA students would take a summer elective in international accounting and gives a survey to a marketing class she was teaching. Which kind of sample is this?

convenience sample

A consistent estimator for the mean

converges on the true parameter μ as the sample size increases.

A news network stated that a study had found a positive correlation between the number of children a worker has and his or her earnings last year. You may conclude that

correlation does not demonstrate causation.

We would create a contingency table by

cross-tabulating frequencies of two variables.

Which component of a time series typically occurs over multiple years?

cycle

The "up-and-down" component of a time series that represents periods of prosperity followed by recession over extended periods of time longer than one year is called

cyclical variation.

One-factor analysis of variance

has less power when the number of observations per group is not identical.

A quadratic trend equation yt = 900 + 80t − 5t2 was fitted to a company's sales. This result implies that the sales trend

hit a peak in period 8.

Given a normal distribution with σ = 3, we want to test the hypothesis H0: μ = 20. We find that the sample mean is 21. The test statistic is

impossible to find without more information.

Which is a necessary assumption of ANOVA?

independent sample observations

The z-test for zero difference in two means

is rarely suitable for business data.

Which is not a poor graphing technique?

labeled axis scales

Which is not a reason for an average student to study statistics?

learn investment strategies

GM's experience with faulty ignition switches suggests that

limited data may still contain important clues.

When the dependent variable is binary (0 or 1), we need

logistic regression

A medical researcher compared the variances in birth weights for five randomly chosen babies of each gender, with the MegaStat results shown below. F-test for equality of variancevariance: Boys3.537variance: Girls3.288F1.08p-value.9453 The population variances

may be assumed equal at any customary α.

A confidence interval for the difference of two population means

may or may not pool the sample variances.

A variable transformation in a regression (e.g., replacing Y with log(Y))

may reduce heteroscedasticity.

To calculate the Pearson 2 coefficient of skewness Sk2 for a sample, we need the

mean, median, and mode.

ANOVA is used to compare

means of several groups.

A valid survey is one that

measures what the researcher wants to measure.

For which binomial distribution would a Poisson approximation not be acceptable?

n = 35, π = .07

For which binomial distribution would a normal approximation be most acceptable?

n = 40, π = .25

In a confidence interval, the finite population correction factor (FPCF) can be ignored when

n = 6 and N = 500.

Refer to the following partial ANOVA results from Excel (some information is missing). Source of VariationSSdfMSFP-valueBetween groups 210.2778 0.064139Within groups1483 74.15 Total2113.833 At α = .05, the difference between group means is

not quite significant.

Two well-known aviation training schools are being compared using random samples of their graduates. It is found that 70 of 140 graduates of Fly-More Academy passed their FAA exams on the first try, compared with 104 of 260 graduates of Blue Yonder Institute. In a right-tailed test, the p-value is .0275, so at α = .025 we should

not reject the hypothesis of equal proportions.

In a random sample of patient records in Cutter Memorial Hospital, six-month postoperative exams were given in 90 out of 200 prostatectomy patients, while in Paymor Hospital such exams were given in 110 out of 200 cases. In comparing these two proportions, normality of the difference may be assumed because

nπ ≥ 10 and n(1 − π) ≥ 10 for each sample taken separately.

Estimating the mean from grouped data will tend to be most accurate when

observations are distributed uniformly within classes.

Systolic blood pressure of randomly selected HMO patients was recorded on a particular Wednesday, with the results shown here: Patient Age GroupUnder 2020 to 2930 to 4950 and Over105110122139113101114115108112128136114127124124123123125123 The appropriate hypothesis test is

one-factor ANOVA.

A binary variable (also called a dichotomous variable or dummy variable) has

only two possible values.

A statistician prepared a bar chart showing, in descending order, the frequency of six underlying causes of general aviation accidents (pilot error, mechanical problems, disorientation, miscommunication, controller error, other). What would we call this type of chart?

pareto chart

Which data would be suitable for a pie chart?

percent vote in the last election by party (Democrat, Republican, Other)

Which type of chart would you use to show the percent of purchases at Starbuck's by payment type (Cash, Gift Card, Starbuck's Card, Apple Pay, Google Pay, Other)?

pie chart or Bar chart

An operations analyst counted the number of arrivals per minute at a bank ATM in each of 30 randomly chosen minutes. The results were: 0, 3, 3, 2, 1, 0, 1, 0, 0, 1, 1, 1, 2, 1, 0, 1, 0, 1, 2, 1, 1, 2, 1, 0, 1, 2, 0, 1, 0, 1. Which goodness-of-fit test would you recommend?

poissonCorrect

"Bob didn't wear his lucky T-shirt to class, so he failed his chemistry exam." This best illustrates which fallacy?

post hoc reasoning

If you were to use Excel to estimate Y = β0 + β1 X + ε with binary Y (0 or 1) you would expect

predicted probabilities greater than 1 or less than 0.

Choosing actions that will result in the best outcome for the company and its customers is

prescriptive analytics.

Comparing a census of a large population to a sample drawn from it, we expect that the

sample is usually a more practical method of obtaining the desired information.

When we are choosing a random sample and we do not place chosen units back into the population, we are

sampling without replacement.

Which chart would be most appropriate to compare last year's CEO compensation in 50 companies with percent operating profit margin in those companies?

scatter plot

Which display is most likely to reveal association between X and Y?

scatter plot

The __________ shows the relationship between two variables.

scatter plot.

The four components of a time series are which of the following?

seasonal, cycle, irregular, trend

Excel's rotated 3D bar charts charts

should be avoided despite their visual appeal.

Pivot tables

show cross-tabulations of data.

Dullco Manufacturing claims that its alkaline batteries last at least 40 hours on average in a certain type of portable CD player. But tests on a random sample of 18 batteries from a day's large production run showed a mean battery life of 37.8 hours with a standard deviation of 5.4 hours. To test DullCo's hypothesis, the p-value is

slightly greater than .05.

"Tom's SUV rolled over. SUVs are dangerous." This best illustrates which fallacy?

small sample generalization

Compared to the area between z = 0.50 and z = 0.75, the area between z = 1.50 and z = 1.75 in the standard normal distribution will be

smaller

When using Chebyshev's Theorem, the minimum percentage of sample observations that will fall within two standard deviations of the mean will be __________ the percentage within two standard deviations if a normal distribution is assumed (Empirical Rule).

smaller than.

Hypothesis tests for a mean using the critical value method require

specifying α in advance.

When predictor variables are strongly related to each other, the __________ of the regression estimates is questionable.

stability

Which is not an assumption of unreplicated two-factor ANOVA (randomized block)?

there is factor interaction

Which issue is least likely arise in machine learning (ML) and artificial intelligence (AI)?

too many skilled programmers with business skills

Because 25 percent of the students in my morning statistics class watch eight or more hours of television a week, I conclude that 25 percent of all students at the university watch eight or more hours of television a week. The most important logical weakness of this conclusion would be

using a sample that may not be representative of all students.

The within-treatment variation reflects

variation among individuals of different groups.

Simple regression analysis means that

we have only one explanatory variable.

A chi-square test of independence is a one-tailed test. The reason is that

we square the deviations, so the test statistic lies at or above zero.

Which is not a characteristic of a dot plot?

wide bins

Which is least likely to involve the application of statistics in business?

writing strategic decisions

Which estimated multiple regression allows a test for nonlinearity?

y = 47 − 12x1 + 8x12 − 5x2 + 25x22

Which estimated multiple regression contains an interaction term?

y = 47 − 12x1 + 8x1x2 − 5x2

Which estimated multiple regression has nonlinearity tests?

y = − 92 − 5x1 + 6x12 + 18x2 − 12x22

Which is a time series?

year-end unemployment rates in the United States, 2000-2010

In a random sample of 810 women employees, it is found that 81 would prefer working for a female boss. The width of the 95 percent confidence interval for the proportion of women who prefer a female boss is

±.0207

In a sample of n = 23, the critical value of the correlation coefficient for a two-tailed test at α = .05 is

±.412.

A random sample of 16 ATM transactions at the Last National Bank of Flat Rock revealed a mean transaction time of 2.8 minutes with a standard deviation of 1.2 minutes. The width (in minutes) of the 95 percent confidence interval for the true mean transaction time is

±0.639

To determine a 72 percent level of confidence for a proportion, the value of z is approximately

±1.08

If the standard error is 12, the width of a quick prediction interval for Y is

±24.

If the standard error is 18, an approximate prediction interval width for Y is

±36.

If μ = 52, σ = 15, and X = 40 the z-score would be

−0.80

In a test for equality of two proportions, the sample proportions were p1 = 12/50 and p2 = 18/50. The test statistic is

−1.31.

−1.728

Group 1 has a mean of 13.4 and group 2 has a mean of 15.2. Both populations are known to have a variance of 9.0 and each sample consists of 18 items. What is the test statistic to test for equality of population means?

−1.800

−1.849.

In the nation of Gondor, the EPA requires that half the new cars sold will meet a certain particulate emission standard a year later. A sample of 64 one-year-old cars revealed that only 24 met the particulate emission standard. The test statistic to see whether the proportion is below the requirement is

−2.000.

When testing the hypothesis H0: μ = 100 with n = 100 and σ2 = 100, we find that the sample mean is 97. The test statistic is

Stats

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