A metropolitan transportation authority has set a bus mechanical reliability goal of 3,900 bus miles. Bus mechanical reliability is measured specifically as the number of bus miles between mechanical road calls. Suppose a sample of 100 buses resulted in a sample mean of 3,975 bus miles and a sample standard deviation of 325 bus miles. Complete parts(a) and(b) below.

The critical values for the test statistic is (are)?

**Test statistic is 2.31**