Suppose a group of 900
smokers (who all wanted to give up smoking) were randomly assigned to receive an antidepressant drug or a placebo for six weeks. Of the 600
patients who received the placebo, 84
were not smoking one year later. Of the 300
patients who received the antidepressant drug, 210
were not smoking one year later. Given the null hypothesis H0:(p1−p2)=0
and the alternative hypothesis Ha:(p1−p2)≠0
, conduct a test to see if taking an antidepressant drug can help smokers stop smoking. Use α=0.01

(a)
The rejection region is |z|>

0

(b)
The test statistic is z=