In a study to compare the effects of two pain relievers it was found that of n1 = 200 randomly selected individuals who used the first pain reliever, 93% indicated that it relieved their pain. Of n2 = 450 randomly selected individuals who used the second pain reliever, 96% indicated 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.