Assume an observational study is conducted to investigate the smoking behaviors of male as well as female patients with a history of coronary heart disease. Among 220 men surveyed, 80 were smokers. Among 190 women surveyed, 95 were smokers.
a. Construct a 95% confidence interval for the difference in the proportions of males and females who smoke.
b. Based on (a), would you reject H0: p1 = p2 in favor of H1: p1 ? p2? Justify your answer briefly.