Business Stats Quizes
The following are the weekly amounts of welfare payments made by the federal government to a sample of six families: $139, $136, $130, $136, $147, and $136. What is the range?
$17
A sample of experienced typists revealed that their mean typing speed is 87 words per minute and the median typing speed is 73 words per minute. The standard deviation of typing speed is 16.9 words per minute. What is the Pearson coefficient of skewness?
+2.5
Manufacturers were subdivided into groups by volume of sales. Those with more than $100 million in sales were classified as large; those from $50 to $100 million as medium size; and those between $25 and $50 million, and so on. Samples were then selected from each of these groups. What is this type of sampling called?
. Stratified random sampling
What is the relative frequency for those salespersons that earn from $1,600 up to $1,800?
.20
An automatic machine inserts mixed vegetables into a plastic bag. Past experience revealed that some packages were underweight and some were overweight, but most of them had satisfactory weight. What is the probability of selecting three packages that are overweight?
0.0004219
Each salesperson in a large department store chain is rated on their sales ability and their potential for advancement. The data for the 500 sampled salespeople are summarized in the following table. What is the probability that a salesperson selected at random will have average sales ability and good potential for advancement?
0.12
A study of interior designers' opinions with respect to the most desirable primary color for executive offices showed that: What is the probability that a designer does not prefer blue?
0.9075
Refer to the following distribution of commissions: For the preceding distribution, what is the midpoint of the class with the greatest frequency?
1,500
What does equal?
10 (6*5*4*3*2*1)(2*1)/(4*3*2*1)(3*2*1) = 10
Percentiles divide a distribution into ________.
100 equal parts
Refer to the following frequency distribution on days absent during a calendar year by employees of a manufacturing company: How many employees were absent from 6 up to 12 days?
20
What is the median of 26, 30, 24, 32, 32, 31, 27, and 29?
29.5
Refer to the following frequency distribution on days absent during a calendar year by employees of a manufacturing company: How many employees were absent between 3 up to 6 days?
31
A sample of wires coming off the production line was tested for tensile strength. The statistical results (in PSI) were the following: According to the Empirical Rule, the middle 95% of the wires tested had a tensile strength between approximately what two values?
420 and 580
Using the following statistics to describe a distribution of data, what is the interquartile range? Minimum = 10 Q1 = 25 Median = 50 Q3 = 75 Maximum = 95
50
A dot plot is best applied for a data set with ________.
50 observations
Over the last six months, the following numbers of absences have been reported: 6, 0, 10, 14, 8, and 0. What is the median number of monthly absences?
7
On a finance exam, 15 accounting majors had an average grade of 90. On the same exam, 7 marketing majors averaged 85, and 10 finance majors averaged 93. What is the weighted mean for all 32 students taking the exam?
89.84
Refer to the following frequency distribution on days absent during a calendar year by employees of a manufacturing company: How many employees were absent fewer than six days?
91
Based on the Empirical Rule, what percent of the observations will lie between plus or minus two standard deviations from the mean?
95%
An investigation of the effectiveness of a training program to improve customer relationships included a pre-training and post-training customer survey. To compare the differences, they computed (post-training survey score - pre-training survey score). Seven customers were randomly selected and completed both surveys. The results follow. This analysis is an example of ________.
A paired t-test
The following graph illustrates ________.
A positive or direct relationship
A dot plot is best applied when ________.
A single variable is summarized
What is the area under the normal curve between z = 0.0 and z = 1.79?
A. 0.4633
The time to fly between New York City and Chicago is uniformly distributed with a minimum of 120 minutes and a maximum of 150 minutes. What is the probability that a flight is between 125 and 140 minutes?
A. 0.50
The tread life of tires mounted on light-duty trucks follows the normal probability distribution with a mean of 60,000 miles and a standard deviation of 4,000 miles. Suppose we select a sample of 40 tires and use a simulator to determine the tread life. What is the likelihood of finding that the sample mean is between 59,050 and 60,950?
A. 0.8664
A random sample of 30 executives from companies with assets over $1 million was selected and asked for their annual income and level of education. The ANOVA comparing the average income among three levels of education rejected the null hypothesis. The Mean Square Error (MSE) was 243.7. The following table summarized the results: When comparing the mean annual incomes for executives with undergraduate and master's degrees or more, the following 95% confidence interval can be constructed:
A. 2.0 ± 2.052 * 6.52
The National Center for Health Statistics reported that of every 883 deaths in recent years, 24 resulted from an automobile accident, 182 from cancer, and 333 from heart disease. What is the probability that a particular death is due to an automobile accident?
A. 24/883 or 0.027
Two accounting professors decided to compare the variance of their grading procedures. To accomplish this, they each graded the same 10 exams, with the following results: What is the critical value of F at the 0.05 level of significance?
A. 3.18
Ball-Bearings, Inc. produces ball bearings automatically on a Kronar BBX machine. For one of the ball bearings, the mean diameter is set at 20.00 mm (millimeters). The standard deviation of the production over a long period of time was computed to be 0.150 mm. What percent of the ball bearings will have diameters of 20.27 mm or more?
A. 3.59%
Mileage tests were conducted on a randomly selected sample of 100 newly developed automobile tires. The mean tread wear was 50,000 miles, with a standard deviation of 3,500 miles. What is the best estimate of the average tread life in miles for the entire population of these tires?
A. 50,000
A research firm wants to compute an interval estimate with 90% confidence for the mean time to complete an employment test. Assuming a population standard deviation of three hours, what is the required sample size if the error should be less than a half hour?
A. 98
The claim that "40% of those persons who retired from an industrial job before the age of 60 would return to work if a suitable job was available" is to be investigated at the 0.02 significance level. If 74 out of the 200 workers sampled said they would return to work, what is our decision?
A. Do not reject the null hypothesis because -0.879 lies in the region between +2.326 and -2.326
The mean annual income of certified welders is normally distributed with a mean of $50,000 and a population standard deviation of $2,000. The ship building association wishes to find out whether their welders earn more or less than $50,000 annually. The alternate hypothesis is that the mean is not $50,000. If the level of significance is 0.10, what is the decision rule?
A. Do not reject the null hypothesis if computed z lies between -1.645 and +1.645; otherwise, reject it.
The results of a mathematics placement exam at two different campuses of Mercy College follow: What is the alternative hypothesis if we want to test the hypothesis that the mean score on Campus 1 is higher than on Campus 2?
A. H1: µ1 > µ2
In regression analysis, what is the predictor variable called? Select one:
A. Independent variable
What is another name for the alternate hypothesis?
A. Research hypothesis
The number of trials and the population proportion are respectively represented by what symbols?
A. n and π
The weekly mean income of a group of executives is $1,000 and the standard deviation of this group is $100. The distribution is normal. What percent of the executives have an income of $925 or less?
About 23%
When TV advertisements report "2 out of 3 dentists surveyed indicated they would recommend Brand X toothpaste to their patients," an informed consumer may question the conclusion because the:
Advertisement does not include the total number of dentists surveyed.
Which of the following measures of dispersion are based on deviations from the mean?
All apply
The result of a particular experiment is called a(n) ________.
Outcome
A student was studying the political party preferences of a university's student population. The survey instrument asked students to identify their political preference—for example, Democrat, Republican, Libertarian, or another party. The best way to illustrate the relative frequency distribution is a
Pie chart
The Nielsen Ratings break down the number of people watching a particular television show by age. What level of measurement is age?
Ratio
The incomes of 50 loan applicants are obtained. Which level of measurement is income?
Ratio
Given the following ANOVA table for three treatments each with six observations: What is the decision regarding the null hypothesis?
Reject H0—there is a difference in treatment means.
The annual dividend rates for a random sample of 16 companies in three different industries, utilities, banking, and insurance were recorded. The ANOVA comparing the mean annual dividend rate among three industries rejected the null hypothesis that the dividend rates were equal. The Mean Square Error (MSE) was 3.36. The following table summarized the results: Based on the comparison between the mean annual dividend rate for companies in utilities and banking, the 95% confidence interval shows an interval of 1.28 to 6.28 for the difference. This result indicates that ________.
B. The annual dividend rate in the utilities industry is significantly less than the annual dividend rate in the banking industry
When testing for differences between treatment means, a confidence interval is computed with
B. The mean square error
If 95% and 98% confidence intervals were developed to estimate the true cost of an MP3 player with a known population standard deviation, what differences would they have?
B. The z statistics would be different.
Assume the least squares equation is Ŷ = 10 + 20X. What does the value of 10 in the equation indicate?
B. When X = 0, Y = 10.
A student was interested in the cigarette smoking habits of college students and collected data from an unbiased random sample of students. The data is summarized in the following table: What type of chart best represents the frequency table?
Bar chart
The net weights (in grams) of a sample of bottles filled by a machine manufactured by Edne, and the net weights of a sample filled by a similar machine manufactured by Orno, Inc., are: Testing the claim at the 0.05 level that the mean weight of the bottles filled by the Orno machine is greater than the mean weight of the bottles filled by the Edne machine, what is the critical value? Assume equal standard deviations for both samples.
C. +1.782
At the .01 significance level, is there a difference in the mean number of times men and women send a Twitter message in a day? What is the p-value for this hypothesis test?
C. 0.0164
The employees of Cartwright Manufacturing are awarded efficiency ratings. The distribution of the ratings approximates a normal distribution. The mean is 400, the standard deviation 50. What is the area under the normal curve between 400 and 482?
C. 0.4495
The mean weight of trucks traveling on a particular section of I-475 is not known. A state highway inspector needs an estimate of the population mean. He selects and weighs a random sample of 49 trucks and finds the mean weight is 15.8 tons. The population standard deviation is 3.8 tons. What is the 95% confidence interval for the population mean?
C. 14.7 and 16.9
Given the least squares regression equation, Ŷ = 1,202 + 1,133X, when X = 3, what does Ŷ equal?
C. 4,601
A research firm needs to estimate within 3% the proportion of junior executives leaving large manufacturing companies within three years. A 0.95 degree of confidence is to be used. Several years ago, a study revealed that 21% of junior executives left their company within three years. To update this study, how many junior executives should be surveyed?
C. 709
The average score of 100 students taking a statistics final was 70, with a standard deviation of 7. Assuming a normal distribution, what test score separates the top 5% of the students from the lower 95% of the students?
C. 81.55
An analysis of the grades on the first test in History 101 revealed that they approximate a normal curve with a mean of 75 and a standard deviation of 8. The instructor wants to award the grade of A to the upper 10% of the test grades. To the nearest percent, what is the dividing point between an A and a B grade?
C. 85
What kind of distribution is the t distribution?
C. Continuous
Suppose we test H0: π1 = π2 at the 0.05 level of significance. If the z-test statistic is -1.07, what is our decision?
C. Do not reject the null hypothesis.
A confidence interval for a population mean ________.
C. Estimates a likely interval for a population mean
A hypothesis regarding the weight of newborn infants at a community hospital is that the mean is 6.6 pounds. A sample of seven infants is randomly selected and their weights at birth are recorded as 9.0, 7.3, 6.0, 8.8, 6.8, 8.4, and 6.6 pounds. The null hypothesis is ________.
C. H0: µ = 6.6
A company is researching the effectiveness of a new website design to decrease the time to access a website. Five website users were randomly selected, and their times (in seconds) to access the website with the old and new designs were recorded. To compare the times, they computed (new website design time - old website design time). The results follow. What is the null hypothesis?
C. H0: µd ≥ 0
It is claimed that in a bushel of peaches, less than 10% are defective. A sample of 400 peaches is examined and 50 are found to be defective. What is the null hypothesis?
C. H0: π ≥ 0.10
In ANOVA, the null hypothesis is:
C. Ho:U1 = U2= U3
Which of the following is a characteristic of the normal probability distribution?
C. It's bell-shaped
When testing the difference between two dependent population means, the test statistic is based on a ________.
C. Standard deviation of the differences
If the correlation between two variables is close to one, the association between the variables is ________.
C. Strong
In the regression equation, what does the letter "b" represent?
C. The slope of the line
When is it appropriate to use the paired difference t-test?
C. When two dependent samples are compared
The null hypothesis for an ANOVA analysis comparing four treatment means is rejected. The four sample means are = 10, = 12, = 15, = 18. The sample size for each treatment is the same. If ( - ) is significantly different from zero, then ________.
C. X1 is significantly less than X2 ,X3 ,X4 .
The regression equation is Ŷ = 29.29 - 0.96X, the sample size is 8, and the standard error of the slope is 0.22. What is the critical value to test the significance of the slope at the 0.01 significance level?
C. t = ±3.707
The mean annual incomes of certified welders are normally distributed with the mean of $50,000 and a standard deviation of $2,000. The ship building association wishes to find out whether their welders earn more or less than $50,000 annually. The alternate hypothesis is that the mean is not $50,000. If the level of significance is 0.10, what is the critical value?
C. ±1.645
A survey of 50 retail stores revealed that the average price of a microwave was $375, with a sample standard deviation of $20. Assuming the population is normally distributed, what is the 95% confidence interval to estimate the true cost of the microwave?
D. $369.31 to $380.69
There are 10 AAA batteries in a box and 3 are defective. Two batteries are selected without replacement. What is the probability of selecting a defective battery followed by another defective battery?
D. 1/15 or about 0.07
Suppose a tire manufacturer wants to set a mileage guarantee on its new XB 70 tire. Tests revealed that the tire's mileage is normally distributed with a mean of 47,900 miles and a standard deviation of 2,050 miles. The manufacturer wants to set the guaranteed mileage so that no more than 5% of the tires will have to be replaced. What guaranteed mileage should the manufacturer announce?
D. 44,518
A random sample of 40 companies with assets over $10 million was surveyed and asked to indicate their industry and annual computer technology expense. The ANOVA comparing the average computer technology expense among three industries rejected the null hypothesis. The Mean Square Error (MSE) was 195. The following table summarized the results: Based on the comparison between the mean annual computer technology expense for companies in the education and tax services industries, _
D. A confidence interval shows that the mean annual computer technology expenses are significantly different
Which of the following are true assumptions underlying linear regression? (1) For each value of X, there is a group of Y values that is normally distributed. (2) The means of these normal distributions of Y values all lie on the regression line. (3) The standard deviations of these normal distributions are equal.
D. All of them
A sales manager for an advertising agency believes that there is a relationship between the number of contacts that a salesperson makes and the amount of sales dollars earned. What is the dependent variable?
D. Amount of sales dollars
For a population that is not normally distributed, the distribution of the sample means will ________.
D. Approach a normal distribution
If an ANOVA test is conducted and the null hypothesis is rejected, what does this indicate?
D. At least one pair of population means is different.
Based on the Nielsen ratings, the local CBS affiliate claims its 11 p.m. newscast reaches 41% of the viewing audience in the area. In a survey of 100 viewers, 36% indicated that they watch the late evening news on this local CBS station. What is your decision if α = 0.01?
D. Fail to reject the null hypothesis.
What is the difference between a sample mean and the population mean called?
D. Sampling error
When dividing a population into subgroups so that a random sample from each subgroup can be collected, what type of sampling is used?
D. Stratified random sampling
A sales manager for an advertising agency believes that there is a relationship between the number of contacts that a salesperson makes and the amount of sales dollars earned. A regression analysis shows the following results: What is the regression equation?
D. Y = -12.201 + 2.195X
A survey of an urban university (population of 25,450) showed that 870 of 1,100 students sampled supported a fee increase to fund improvements to the student recreation center. Using the 95% level of confidence, what is the confidence interval for the proportion of students supporting the fee increase?
D. [0.767, 0.815]
The standard deviation of any uniform probability distribution is _
D. square root of (b - a)^2/12.
What type of variable is the number of auto accidents reported in a given month?
Discrete
A survey includes a question regarding marital status that has the following responses: single, married, divorced, separated, or widowed. What is the scale of measurement for this question?
Select one: Nominal
What statistics are needed to draw a box plot?
The minimum, maximum, median, first and third quartiles.
A sample mean is the best point estimate of
The population mean
All possible samples of size n are selected from a population and the mean of each sample is determined. What is the mean of the sample means?
The population mean
What does the interquartile range describe?
The range of the middle 50% of the observations
If two events are independent, then their joint probability is computed with
The special rule of multiplication
A group of 100 students were surveyed about their interest in a new Economics major. Interest was measured in terms of high, medium, or low. In the study, 30 students responded high interest, 50 students responded medium interest, and 20 students responded low interest. What is the best way to illustrate the relative frequency of student interest?
Use a pie chart
In a distribution, the second quartile corresponds with the ________.
Median
Shoe style is an example of what level of measurement?
Nominal
The Equal Employment Opportunity Act requires employers to classify their employees by gender and national origin. Which level of measurement is this?
Nominal
What level of measurement is a person's "favorite sport"?
Nominal
Which one of the following is NOT an example of discrete data?
Number of miles between New York City and Chicago
When a class interval is expressed as 100 up to 200, ________.
Observations with values of 200 are excluded from the class
It is claimed that in a bushel of peaches, less than 10% are defective. A sample of 400 peaches is examined and 50 are found to be defective. What is the z-test statistic?
B. +1.667
The Intelligence Quotient (IQ) test scores for adults are normally distributed with a mean of 100 and a standard deviation of 15. What is the probability we could select a sample of 50 adults and find the mean of this sample is less than 95?
B. 0.0091
In a management trainee program, 80% of the trainees are female, 20% male. A total of 90% of the females attended college, while 78% of the males attended college. A management trainee is selected at random. What is the probability that the person selected is a male who did NOT attend college?
B. 0.044
Bones Brothers & Associates prepare individual tax returns. Over prior years, Bones Brothers has maintained careful records regarding the time to prepare a return. The mean time to prepare a return is 90 minutes and the standard deviation of this distribution is 14 minutes. Suppose 100 returns from this year are selected and analyzed regarding the preparation time. What is the probability that the mean time for the sample of 100 returns is between 88 minutes and 92 minutes?
B. 0.8472
A board of directors consists of eight men and four women. A four-member search committee is randomly chosen to recommend a new company president. What is the probability that all four members of the search committee will be women?
B. 1/495 or 0.002
If the critical z value for a hypothesis test equals 2.45, what value of the test statistic would provide the least chance of making a Type I error?
B. 10,000
A marketing firm is studying consumer preferences for winter fashions in four different months. From a population of women 18-21 years of age, a random sample of 100 women was selected in January. Another random sample of 100 women was selected in March. Another random sample of 100 women was selected in June. Another random sample of 100 women was selected in September. What is the number of samples?
B. 4
A sales manager for an advertising agency believes there is a relationship between the number of contacts that a salesperson makes and the amount of sales dollars earned. A regression analysis shows the following results: = 33.4. = 2814.4. Rounding to one decimal place, the 95% confidence interval for 30 calls is ________.
B. 46.7, 60.6
Two accounting professors decided to compare the variance of their grading procedures. To accomplish this, they each graded the same 10 exams, with the following results: What is the critical value of F at the 0.01 level of significance?
B. 5.35
A bank wishes to estimate the mean credit card balance owed by its customers. The population standard deviation is estimated to be $300. If a 98% confidence interval is used and an interval of $75 is desired, how many customers should be sampled?
B. 87
A recent study focused on the amount of money single men and women save monthly. The information is summarized next. Assume that the population standard deviations are equal. At the .01 significance level, what is the conclusion about the way women and men save?
B. Fail to reject the null hypothesis.
When testing the hypothesized equality of two population means, the implied null hypothesis is _
B. H0: µ1 - µ2 = 0
For any data set, which measures of central location have only one value?
Mean and median
Refer to the following breakdown of responses to a survey of "How confident are you that you saved enough to retire?" What is the class with the greatest frequency?
Somewhat confident
If the variance of the "number of daily parking tickets" issued is 100, the standard deviation is defined as the
Square root of the variance of the "number of daily parking tickets"
The general process of gathering, organizing, summarizing, analyzing, and interpreting data is called
Statistics
What is the relationship among the mean, median, and mode in a symmetric distribution?
They are all equal.
In a contingency table, we describe the relationship between ________.
Two variables measured at the ordinal or nominal level
