Question: Confidence interval for comparing diets: A randomized trial tested the effectiveness of diets on adults. Among 40 subjects using the weight watchers diet, the mean weight loss after one year was 3.0 lbs, with a standard deviation of 4.9 lbs. Among 40 subjects using the Atkins diet, the mean weight loss after one year was 2.1 lbs, with a standard deviation of 4.8 lbs. Construct a 95 percent confidence interval estimate about the differences between the two population means. Does there appear to be a difference in the effectiveness of the two diets? Does the amount of weight loss appear to justify either diet?