Problem 8.39 In a weight loss experiment 10 men followed diet A and 7 men followed diet B. The weight losses after one month are displayed in the following table. Diet A Diet B Diet A Diet B 15.3 3.4 10 5.2 2.1 10.9 8.3 2.5 8.8 2.8 9.4 5.1 7.8 12.5 8.3 0.9 11.1

(a) Use the two sample t test to determine if there is any significant difference between the two diets. Assume the data are normally distributed with a common variance; use α = 0.05. In detail: Describe the null and alternative hypotheses, and determine which diet is more effective in reducing weight.

(b) Use the Wilcoxon rank sum test to test H0 : µ1 = µ2 against H1 : µ1 > µ2. Use α = 0.05. What is the P-value of the test? Remember that diet B is now population 1 because its sample size is the smaller one.