Women on average have 8 more pairs of shoes than men, according to a USA Today Snapshot titled “Who owns more shoes?” (July 8, 2009). A recent study at a community college gave the following results:
a. Find the 90% confidence interval for the difference between the two mean numbers of pairs of shoes for males and females.
b. Does the confidence interval found in part a agree with the statement made in the USA Today Snapshot? Explain.
c. Is the claim “average 8 more” one-sided (“at least 8 more”), or is it two-sided (meaning “not less than 8 or not more than 8”)? Explain how you would interpret the claim.