Suppose the data in Exercise 7.99 are based on independent random samples.

a. Do the data provide sufficient evidence to indicate a difference between the mean strengths for the two types of shocks? Use a = .05.

b. Construct a 95% confidence interval for (p, - p2).

Interpret your result.

c. Compare the confidence intervals you obtained in Exercise 7.99 and in part b of this exercise. Which is wider? To what do you attribute the difference in width? Assuming in each case that the appropriate assumptions are satisfied, which interval provides you with more information about (p, - p2)? Explain.

d. Are the results of an unpaired analysis valid if the data come from a paired experiment?