For Exercises 7–12, a random sample is drawn from a normal population. For each exercise, do the following:

  1. State the hypotheses.
  2. Find the critical values and state the rejection rule.
  3. Calculate .
  4. Compare with the critical value or values. State the conclusion and interpretation.

Question 9.334

11. Test whether , using . We have a sample of size and a sample variance of .

9.6.11

(a) (b) . Reject if . (c) (d) Since is not , we do not reject . There is insufficient evidence that the population standard deviation is less than 20.