Are low-fat diets or low-carb diets more effective for weight loss? A sample of 77 subjects went on a low-carbohydrate diet for six months. At the end of that time, the sample mean weight loss was 4.7 kilograms with a sample standard deviation of 7.16 kilograms. A second sample of 79 subjects went on a low-fat diet. Their sample mean weight loss was 2.6 kilograms with a standard deviation of 5.90 kilograms.

Can you conclude that the mean weight loss differs between the two diets? Use the α = 0.01 level.

a. State the appropriate null and alternate hypotheses.

b. Compute the test statistic.

c. How many degrees of freedom are there, using the simple method?

d. Do you reject H0? State a conclusion.