Smoking cessation trial. A randomized controlled, double-blind trial was conducted to see whether sustained-release bupropion (a pharmaceutical normally used to treat depression) provided benefit over use of the nicotine patch alone in helping people stop smoking.

The control group (nicotine patch alone) included 244 smokers who wanted to stop smoking. The treatment group consisting of 245 individuals received sustained-release bupropion in combination with a nicotine patch. After 1 year, 40 individuals in the control group remained smoke-free. In contrast, 87 in the treatment group had done the same.m

(a) Calculate the incidence proportions of cessation in the groups.

(b) Test the difference in proportions for significance. (Show all hypothesis-testing steps.)

(c) Concisely summarize the results of the study.