For Exercises 15–26, do the following:

  1. State the hypotheses and the rejection rule using the -value method.
  2. Calculate the test statistic .
  3. Find the -value. (Use technology or estimate the -value.)
  4. State the conclusion and the interpretation.

Question 9.221

25. A random sample of size 9 from a normal population yields and . Researchers are interested in finding whether the population mean differs from 0, using level of significance .

9.4.25

(a) . Reject if the (b) (c) 0.0003 (d) Since the is , the conclusion is reject . There is evidence at the 0.05 level of significance that the population mean differs from 0.