8.69 Excedrin or Tylenol? In a study to compare the effects of two pain relievers, it was found that of n = 200 randomly selected individuals instructed to use the first pain reliever, 93% indicated that it relieved their pain. Of n 450 randomly selected individuals instructed to use the second pain reliever, 96% indi- cated that it relieved their pain.

a. Find a 99% confidence interval for the difference in the proportions experiencing relief from pain for these two pain relievers.

b. Based on the confidence interval in part

a, is there sufficient evidence to indicate a difference in the proportions experiencing relief for the two pain relievers? Explain.