Final Exam BNAL 206

An entrepreneur is considering the purchase of a coin-operated laundry. The current owner claims that the mean daily revenue was $675 with a population standard deviation of $75. A sample of 30 days reveals a daily mean revenue of $625. Using the information provided, calculate the value of the test statistics for the hypothesis testing.

-3.65

Major league baseball salaries averaged $3.26 million with a standard deviation of $1.2 million in a certain year in the past. Suppose a sample of 100 major league players was taken. Find the approximate probability that the mean salary of the 100 players was not more than $3 million.

0.0150 standard error of the mean = 1.2/sqrt(100)= 0.12 P(X<3) = norm.dist(3,3.26,0.12,true) = 0.015

A certain type of new business succeeds 60% of the time. Suppose that 3 such businesses open in three different cities. Assume that the relative success of each business would be independent. The probability that all 3 businesses fail is: ___________.

0.064 P(x=0| n=3, p= 0.6) There is only one possibility: (binomial) =BINOM.DIST(0,3,0.6,0). = 0.064 or = (3!/0! (3-0)!) (0.6)^0 (1-0.6)^3 = = (1) (1) (1-0.6)^3 =0.064

The amount of time necessary for assembly line workers to complete a product is a normal variable with a mean of 15 minutes and a standard deviation of 2 minutes. The probability is __________ that a product is assembled in less than 12 minutes.

0.0668 P(X<12) norm.dist (12,15,2,true) = 0.0668 or Z= (12-15) /2= -1.5 Look for Z = -1.5 in the table --> 0.0668

Suppose A and B are mutually exclusive events where P(A) = 0.05 and P(B) = 0.02. What is P (A or B) ?

0.07 As the events are mutually exclusive, P(A or B) = P(A) + P(B) = 0.05+0.02=0.07

The Department of Commerce in a state has determined that the number of small businesses that declare bankruptcy per month is approximately a Poisson distribution with a mean of 6.4. Find the probability that exactly 5 bankruptcies occur next month.

0.149 P(X=5 | λ= 6.4) = =POISSON.DIST(5,6.4,FALSE) = 0.149 or =e−λλxx! = e−6.4(6.4)55!=0.149

Suppose A and B are events where P(A) = 0.4, P(B) = 0.5, and P (A and B) = 0.1. What is P(A|B)?

0.2

The probability that a new advertising campaign will increase sales is 0.80. The probability that the cost of the new ad campaign can be kept within the original budget is 0.40. If the two events are independent, the probability that the cost is kept within budget AND the campaign will increase sales is:

0.32

The profit from selling folding tables varies uniformly each quarter between $1,500 and $2,300. What is the probability that profit will be less than $1,900?

0.5 F (x) = (x-a)/(b-a) a = 1500, b= 2300, x = 1900 F(1,900) = (1,900 - 1,500) / (2,300 - 1,500) = 0.50

The amount of time necessary for assembly line workers to complete a product is a normal variable with a mean of 15 minutes and a standard deviation of 2 minutes. The probability is __________ that a product is assembled in more than 11 minutes.

0.9772 P(X>11) norm.dist(11,15,2,true) = 0.0228 or Z= (11-15) /2= -2 Look for Z = -2.0 in the table --> 0.0228 P(X> 100) = 1- 0.0228 = 0.9772

If two events are mutually exclusive and collectively exhaustive, what is the probability that one or the other occurs?

1

If we consider 10 trials and the probability of the event of interest is 0.70, then the standard deviation of the binomial distribution is _____________.

1.45

We want to estimate the true proportion of statistics students who are female. In a random sample of 72 statistics students, 39 were female. What sample size would be necessary if we want to estimate the true proportion within +/- 0.08 using 95% confidence?

150

The amount of time required for an oil and filter change on an automobile is normally distributed with a mean of 45 minutes and a standard deviation of 10 minutes. A random sample of 16 cars is selected. What is the standard error of the mean?

2.5 std error of the mean = 10/SQRT(16) = 2.5

The length of time it takes a college student to find a parking spot in the library parking lot follows a normal distribution with a mean of 3.5 minutes and a standard deviation of 1 minute. 33% of the college students will take less than how many minutes when trying to find a parking spot in the library parking lot?

3.06 Probability = 0.33 norm.inv(0.33, 3.5,1) = 3.06 or Look for 0.33 in the table --> Z = -0.44 X = μ + Z σ = 3.5 + (-0.44) 1 = 3.06

Below is a spreadsheet of purchase orders for a computer hardware retailer. What will be the result of the function VLOOKUP(1004, A2:H7,6)?

300

The retail association wants to estimate the population mean wage of store managers. A sample of 49 managers reveals a sample mean of $45,420. The population standard deviation is known to be $2,050. What is the lower confidence limit in a 95% confidence interval for the mean wage?

44,846

The contingency table below contains the number of people who own a portable Blu-ray player in a sample of 600 people broken down by gender. Own a Bluray player Male Female Total Yes 96 40 136 No 224 240 464 Total 320 280 600 Of those who did not owned a portable Blu-ray player in the sample, which percent were males?

48.3%

Four hundred accidents that occurred on a Saturday night were analyzed by the number of cars involved and if the alcohol played a role. a. what is the probability that an accident involved a single car and alcohol played a role?

50/400

The manager of a restaurant wants to estimate the mean expenditure per visit at the restaurant. A sample of 20 customers revealed a sample mean of $49.35 with a sample standard deviation of $9.01. Compute the upper confidence interval for the population mean for a confidence level of 95%.

53.57

Suppose a department store wants to estimate the mean age of the customers of its contemporary apparel department, correct to +/- 2 years, with level of confidence equal to 95%. Management believes that the standard deviation is 8 years. The sample size they should take is

62

Subway offers a menu with 3 different breads, 4 types of cheese, 2 types of meat and 3 types of vegetables. If you want to include one choice from each ingredient category, how many different sandwiches can you build?

72 3 different breads, 4 type of cheese, 2 types of meat and 3 types of vegetables outcomes = 3x4x2x3 = 72

Below is the spreadsheet for demand prediction of a company that sells chocolates. Given that D = a - bP, where D, is demand, "a" and "b," are linear constants, and P, is price, from the above spreadsheet, how will the formula in B9 be represented in Excel using relative references?

=B4-B5*A9

In the spreadsheet below, there is data on the price, cost, and quantity produced for an item.

=B6*B8+B7

Below is a list of purchase orders for a computer hardware retailer.

=COUNTIFS(H2:H6, "Small", A2:A6, "Rex Technologies")

Below is a spreadsheet of purchase orders for a computer hardware retailer. Which of the following Database functions calculates the count of purchase orders made by Rex Technologies?

=DCOUNT(A3:H8,"Item Cost",A1:H2)

Below is a spreadsheet of purchase orders for a computer hardware retailer. Which of the following Database functions calculates the total cost charged to Rex Technologies for large size orders?

=DSUM(A3:H8,"Cost per Order",A1:H2)

Below is a spreadsheet of purchase orders for a computer hardware retailer. If purchase quantities of 25 units or higher are found to be "large" orders, and orders less than 25 are considered to be "small", what IF function should be entered in H2 to assign each order's size?

=IF(D2>=25,"Large","Small")

Below is a spreadsheet of purchase orders for a computer hardware retailer.

=SUMIF(A2:A7, "Rex Technologies", D2:D7)

Which of the following is true about cross-tabulation?

All subcategories together must constitute the complete data set.

Which of the following is a differentiation between calculating using the functions COUNT and COUNTIF?

COUNT only requires a range of cells, COUNTIF requires range and special criteria to be calculated.

Which of the following is true about constructing PivotTables?

Dragging a field into the Filter area allows addition of a third dimension to the analysis.

Which of the following is a valid one-sample hypothesis test?

H 0: population parameter = constant H 1: population parameter ≠ constant

Which is NOT a method to create range names in Excel?

Highlight and drag down

________ is a logical function that returns one value if the condition is true and another if the condition is false.

IF (condition, value if true, value if false)

Which of the following about the normal distribution is not true?

It is a discrete probability distribution

Which of the following statements about the median is not true?

It is more affected by extreme values than the arithmetic mean

Which of the following is true about variance for a random variable?

It measures the uncertainty of a random variable.

Sales prices of baseball cards from the 1960s are known to have a right skewed distribution with a mean sale price of $5.25 and a standard deviation of $2.80. Suppose a random sample of 100 cards is selected. Describe the sampling distribution for the sample mean sale price of the selected cards.

Normal with a mean of $5.25 and a standard error of $0.28.

In the advanced filter, multiple criteria in different rows are logically joined by _____.

OR

________ sampling applies to populations that are divided into natural subsets and allocates the appropriate proportion of samples to each subset.

Stratified

Which of the following is true of the binomial distribution?

The binomial distribution can assume different shapes, depending on the parameters.

Which of the following is true of the Poisson distribution?

The number of events that occur in one interval is independent of the number of events that occur in any other interval.

Which of the following about the binomial distribution is not a true statement?

The variable of interest is continuous.

A manager of the credit department for an oil company would like to determine whether the mean monthly balance of credit card holders is equal to $75. An auditor selects a random sample of 100 accounts and finds that the mean owed is $83.40 with a sample standard deviation of $23.65. If you wanted to test whether the mean balance is different from $75 and decided to reject the null hypothesis, what conclusion could you reach? (no computation needed)

There is enough evidence to conclude that the mean balance is different from $75. If you were to test the null hypothesis that the mean balance is $75 and decide to reject the null hypothesis, there is enough evidence to conclude that the mean balance is different from $75.

A university dean is interested in determining the proportion of students who receive some sort of financial aid. Rather than examine the records for all students, the dean randomly selects 200 students and finds that 118 of them are receiving financial aid. The 95% confidence interval for the population proportion is 0.59 +/- 0.07. Interpret this interval.

We are 95% confident that the true proportion of all students receiving financial aid is between 0.52 and 0.66

If, as a result of a hypothesis test, you reject the null hypothesis when it is true, then you have committed

a Type I error

The manager of the customer service of a major consumer electronics company is interested in determining whether the customers who have purchased a Blue-ray player over the past 12 months are satisfied with their products. If there are 4 different brands of Blu-ray players made by the company, the best sampling strategy would be to use a

a stratified sample

Nominal data:

are sorted into categories according to specified characteristics.

A probability density function:

characterizes outcomes of a continuous random variable.

Below is a spreadsheet of purchase orders for a computer hardware retailer. For which of the following columns can the COUNT function be performed?

column E

A ________ is a range of values between which the value of the population parameter is believed to be, along with a probability that the interval correctly estimates the true population parameter.

confidence interval

blank can be defined as numbers or textual data that are collected through some type of measurement process

data

A manager at Gampco Inc. wishes to know the company's revenue and profit in its previous quarter. Which of the following business analytics will help the manager?

descriptive analytics

Predictive analytics:

detects patterns in historical data and extrapolates them forward in time.

In sampling, ________ involves assessing the value of an unknown population parameter—such as a population mean, population proportion, or population variance—using sample data.

estimation

The easiest way to locate a particular function is to select a cell and click on the Insert function button represented by ________ on the Excel ribbon.

fx

Which of the following is NOT a challenge for business analytics?

having sufficient analytical skills

For a one-tailed test, the critical value:

helps determine if the test statistic falls in the rejection region or not.

If a test of hypothesis has a Type I error probability (α) of 0.05, it means that

if the null hypothesis is true, you reject it 5% of the time.

Which of the following statements is incorrect about the standard error of the mean (or standard deviation of the sampling distribution):

increases when the sample size increases

In a survey, the possible responses to the question "What is your credit score?" are values from a ________ type of measurement scale.

interval

Using a $ sign before a row number and a column label ________.

keeps the reference to both the row and column fixed

You have collected data on the monthly seasonally adjusted civilian unemployment rate for the United States over a 10-year period. Which of the following is the best for presenting the data?

line chart

The exponential distribution:

models the time between randomly occurring events.

In the construction of confidence intervals, if all other quantities are unchanged, an increase in the sample size will lead to a ________________ interval.

narrower if we increase the sample size, the confidence interval will be narrower.

The purpose of sampling is to ________.

obtain sufficient information to draw a valid inference about a population

A__________ summarizes the value of a population for a specific variable.

parameter

Which decision model incorporates the process of optimization?

prescriptive

In the rows of a two-dimensional table, we will find

records

The central limit theorem states that if the population is normally distributed, then the ________.

sampling distribution of the mean will also be normal for any sample size

The difference between the upper limit of a confidence interval and the point estimate used in constructing the confidence interval is called _______________________.

sampling error

What is a dataset?

simply a collection of data

Sampling distributions describe the distribution of

statistics

During which phase in problem solving is a formal model often developed?

structuring the problem

A manager of the credit department for an oil company would like to determine whether the mean monthly balance of credit card holders is equal to $75. An auditor selects a random sample of 100 accounts and finds that the mean owed is $83.40 with a sample standard deviation of $23.65. If you were to conduct a test to determine whether the auditor should conclude that there is evidence that the mean balance is different from $75, which test would you use?

t-test of population mean As the population standard deviation is not known for testing the population mean, the correct test is t-test for the population mean

If Z= -2.5, it means that

the value is 2.5 standard deviations below the mean

If the sample covariance between the rating and the performance scores of different laptop computers is 88.9, you can infer that

the variables move in the same direction

In a _______-tailed test, the significance level is divided equally between the two tails.

two

The concept of ___________ refers to the case in which data correctly measures what it is supposed to measure .

validity

Big data refers to four concepts:

volume, variety, velocity and veracity

Which of the following is an example of a measure of continuous metrics?

weight and volume of a sheet of steel