For Exercises 7–12, a random sample is drawn from a normal population. For each exercise, do the following:
9. Test whether , using . We have a sample of size and a standard deviation of .
9.6.9
(a) (b) and . Reject if or . (c) (d) Since is not and is not , we do not reject . There is insufficient evidence that the population standard deviation is different from 3.