Step 1 :Identify the null and alternative hypotheses for this test. The null hypothesis (H0) is usually a statement of no effect or no difference. In this case, the null hypothesis would be that the proportion of smokers who are still smoking one year after treatment is equal to 0.5 (or 50%). The alternative hypothesis (H1) is what we are testing against the null hypothesis. In this case, we are testing the claim that the majority of smokers are still smoking one year after treatment, so the alternative hypothesis would be that the proportion of smokers who are still smoking one year after treatment is greater than 0.5. The correct answer is: \[ \begin{array}{l} H_{0}: p=0.5 \\ H_{1}: p>0.5 \end{array} \]
Step 2 :Identify the test statistic for this hypothesis test. The test statistic for this hypothesis test can be calculated using the formula for the z-score, which is \((p̂ - p0) / \sqrt{(p0 * (1 - p0)) / n}\), where p̂ is the sample proportion, p0 is the hypothesized population proportion in the null hypothesis, and n is the sample size.
Step 3 :In this case, p̂ is the proportion of smokers who are still smoking one year after treatment, which is 39 / (39 + 31) = 0.557. p0 is the hypothesized population proportion in the null hypothesis, which is 0.5. And n is the sample size, which is 39 + 31 = 70.
Step 4 :Substitute the values into the z-score formula to get the test statistic: \(z = (0.557 - 0.5) / \sqrt{(0.5 * (1 - 0.5)) / 70} = 0.96\)
Step 5 :The test statistic for this hypothesis test is \(\boxed{0.96}\)