For Exercises 21–26, assume that the populations are independent and normally distributed. Perform the indicated hypothesis tests using the critical-value method. For each exercise
21.
10.4.21
(a) (b) . Reject if . (c) . (d) Since is not , we do not reject . There is insufficient evidence at the level of significance that the population standard deviation of Population 1 is greater than the population standard deviation of Population 2.