specimens of this mixture is normally distributed with 60.

Chapter 8, Problem 8.11

(choose chapter or problem)

specimens of this mixture is normally distributed with 60. Let denote the true average compressive strength. a. What are the appropriate null and alternative hypotheses? b. Let Xdenote the sample average compressive strength for n 20 randomly selected specimens. Consider the test procedure with test statistic X and rejection region x 1331.26. What is the probability distribution of the test statistic when H0 is true? What is the probability of a type I error for the test procedure? c. What is the probability distribution of the test statistic when 1350? Using the test procedure of part (b), what is the probability that the mixture will be judged unsatisfactory when in fact 1350 (a type II error)? d. How would you change the test procedure of part (b) to obtain a test with significance level .05? What impact would this change have on the error probability of part (c)? e. Consider the standardized test statistic Z (X 1300)/(/n) (X 1300)/13.42. What are the values of Z corresponding to the rejection region of part (b)? 11. The ca