A group of 78 people enrolled in a weight-loss program that involved adhering to a special diet and to a daily exercise program. After six months, their mean weight loss was 25 pounds, with a sample standard deviation of 9 pounds. A second group of 43 people went on the diet but didn’t exercise. After six months, their mean weight loss was 14 pounds, with a sample standard deviation of 7 pounds.

Construct a 95% confidence interval for the mean difference in weight losses.