A survey of 15 large U.S. cities finds that the average commute time one way is 25.4 min. A chamber of commerce executive feels that the commute in his city is less and wants to publicize this. He randomly selects 25 commuters and finds the average is 22.1 minutes with a standard deviation of 5.3 minutes. At = 0.17, is he correct? Assume a normal distribution.

a. The critical value for this test is:

b. Suppose the test statistic turns out to be - 2.56 should the null hypotheses be rejected.