Question 1:

Records show that the average commute time for a person living in Atlanta in 2000 was 42 minutes. An analyst claims that the average commute time in 2007 was longer. The analyst takes a simple random sample of thirteen commuters in 2007 and calculates an average of 46.4 and a standard deviation of 3.8. (It is reasonable to assume that the population of commute times has a normal distribution.)

Which of the following is the appropriate test statistic?

a) t = (46.4 - 42.0)/(3.8/13)

b) z = (42.0 - 46.4)/(3.8/13)

c) z = (46.4 - 42.0)/(3.8/13)

d) t = (42.0 - 46.4)/(3.8/13)

e) None of the above

Question 2:

An antiques dealer claims that the average selling price of a certain collectible item on eBay is $5.75. You believe that the average is lower. You select a random sample and find a mean of $5.50. The standard error for your sample is $0.102. Which of the following best describes the P-value in this situation?

a) The probability of getting a sample mean of $5.75 or more if the population mean is actually $5.50.

b) The probability of getting a sample mean of $5.75 or more if the population mean is actually more than $5.50.

c) The probability of getting a sample mean of $5.50 or less if the population mean is actually less than $5.75.

d) The probability of getting a sample mean of $5.50 or less if the population mean is actually $5.75.

e) The probability of getting a population mean lower than $5.75.

Question 3

Based on data, here is a regression line comparing the variables y = mass of a bar of soap in grams and x = number of days soap has been used: Predicted y = 78.5 - 1.8x. Choose the correct interpretation for the slope:

a) A brand-new bar of soap that has been used zero days will be approximately 78.5 grams.

b) For every gram in mass, the predicted number of days it takes to lose that mass is 1.8.

c) For every day the soap is used, the predicted mass of the soap will increase by 1.8 grams.

d) For every day the soap is used, the predicted mass of the soap will decrease by 1.8 grams.

e) For every gram in mass, the predicted number of days it takes to gain that mass is 1.8 days.

Question 4:

Suppose you are trying to test whether blood pressure medicine was useful in reducing a patient's blood pressure, but you know that a nonparametric test is needed because certain conditions have not been met. Which of the tests below would be appropriate for this situation?

I. Rank-sum test

II. Sign test for matched pairs

III. Spearman rank correlation test

a) All three tests

b) None of these tests

c) I and II only

d) II and III only

e) II only

Question 5:

In a Spearman rank correlation test, if two of the values are the same, choose the correct answer below for what to do for those two values:

a) Since they are duplicates, omit both of them from the data

b) Since they are duplicates, omit one of them from the data

c) Just rank them as usual, even if it means they will have different ranks

d) Average the ranks together and use the average rank for both values

e) A Spearman rank correlation test cannot be done if two values or more are the same; new data will need to be collected