Example 5.5 (page 129) analyzed data from a study that compared therapies for anorexia. For the 17 girls who received the family therapy, the changes in weight during the study (which are in the data file Anorexia at the text website) were 11, 11, 6, 9, 14,−3, 0, 7, 22,−5,−4, 13, 13, 9, 4, 6, 11.

(a) Verify that ¯y = 7.29, s = 7.18, and se = 1.74.

(b) To use the t distribution, explain why df = 16 and a 95% confidence interval uses the t-score of 2.120.

(c) Verify that the 95% confidence interval for the population mean change in weight μ for this therapy is (3.6, 11.0). Interpret.