Consider the chemical etch rate data in Exercise 10-23.

(a) Use the Wilcoxon rank-sum test to investigate the claim that the mean etch rate is the same for both solutions. If α = 0.05, what are your conclusions?

(b) Use the normal approximation for the Wilcoxon rank-sum test. Assume that α = 0.05. Find the approximate P-value for this test. 10-45. 

Consider the pipe deflection data in Exercise 10-22.

(a) Use the Wilcoxon rank-sum test for the pipe deflection temperature experiment. If α = 0.05, what are your conclusions?

(b) Use the normal approximation for the Wilcoxon rank-sum test. Assume that α = 0.05. Find the approximate P-value for this test.