1) Sony would like to test the hypothesis that the average age of a PlayStation user is different from the average age of an Xbox user. A random sample of 32 PlayStation users had an average age of 33.7 years while a random sample of 36 Xbox users had an average age of 35.6 years. Assume that the population standard deviation for the age of PlayStation and Xbox users is 3.7 and 3.5 years, respectively. Sony would like to set =0.05. Which one of the following statements is true?

A.Because the 95% confidence interval includes zero, we fail to reject the null hypothesis and can conclude that the average age of PlayStation users is different from the average age of Xbox users.

B.Because the 95% confidence interval does not include zero, we fail to reject the null hypothesis and can conclude that the average age of PlayStation users is different from the average age of Xbox users.

C.Because the 95% confidence interval includes zero, we fail to reject the null hypothesis and conclude that the average age of PlayStation users is equal to the average age of Xbox users.

D.Because the 95% confidence interval does not include zero, we reject the null hypothesis and can conclude that the average age of PlayStation users is different from the average age of Xbox users.

2)The Department of Housing and Urban Development (HUD) would like to test the hypothesis that the average size of a newly constructed house in 2010 is different from the average size of a newly constructed house in 2000. The following data summarizes the sample statistics for house sizes, in square feet, for both years. Assume that the population variances are equal.

	2000	2010
Sample mean	2,180	2,390
Sample size	15	12
Sample standard deviation	300	320

If Population 1 is defined as homes built in 2000 and Population 2 is defined as homes built in 2010, which one of the following statements is true?

A.Because the 95% confidence interval includes zero, HUD cannot conclude that the average size of a newly constructed house in 2010 is different from the average size of a newly constructed house in 2000.

B.Because the 95% confidence interval does not include zero, HUD can conclude that the average size of a newly constructed house in 2010 is different from the average size of a newly constructed house in 2000.

C.Because the 95% confidence interval includes zero, HUD can conclude that the average size of a newly constructed house in 2010 is equal to the average size of a newly constructed house in 2000.

D.Because the 95% confidence interval does not include zero, HUD can conclude that the average size of a newly constructed house in 2010 is not different from the average size of a newly constructed house in 2000.

3) You have been assigned to test the hypothesis that the average number of hours per week that a citizen of Country A works is higher than the average number of hours per week that a citizen of Country B works. The following data summarizes the sample statistics for the number of hours worked per week for workers in each country. Assume that the population variances are unequal.

	Country A	Country B
Sample mean	32.7 hours	28.2 hours
Sample size	15	12
Sample standard deviation	5.1 hours	6.0 hours

If Population 1 is defined as workers from Country A and Population 2 is defined as workers from Country B, the degrees of freedom for this hypothesis test are ________.

A.27

B.26

C.25

D.21

4)Suppose a restaurant chain has run a major advertising campaign in the hopes of increasing monthly sales. To investigate the effectiveness of this campaign, the chain randomly selected seven restaurants and recorded the monthly sales before and after the advertising. The following data represents these sales figures in thousands of dollars.

Restaurant	1	2	3	4	5	6	7
After	$127	$122	$145	$156	$160	$134	$108
Before	$107	$110	$143	$168	$145	$125	$98

If Population 1 is defined as the year 2012 and Population 2 is defined as the year 2011, the standard deviation of the matched-pair differences is ________. Round to two decimal places.

A.9.00

B.7.50

C.10.41

D.14.72

5)The Dean of the Business School at State University would like to test the hypothesis that no difference exists between the average final exam grades for the Introduction to Marketing course and the Introduction to Finance course. A random sample of eight students who took both courses was selected and their final exam grades for each course are shown below.

Student	1	2	3	4	5	6	7	8
Marketing	82	86	74	93	90	76	87	100
Finance	76	91	70	79	96	70	85	81

If Population 1 is defined as the Marketing exam scores and Population 2 is defined as the Finance exam scores, the mean of the matched-pair differences is ________. Round to one decimal place.

A.8.3

B.5.0

C.12.5

D.14.8