10.21 Bulimia CI A study of bulimia among college women

(J. Kern and T. Hastings, Journal of Clinical Psychology, vol. 51, 1995, p. 499) studied the connection between childhood sexual abuse and a measure of family cohesion

(the higher the score, the greater the cohesion). The sample mean on the family cohesion scale was 2.0 for 13 sexually abused students 1s = 2.12 and 4.8 for 17 nonabused students 1s = 3.22.

a. Find the standard error for comparing the means.

b. Construct a 95% confidence interval for the difference between the mean family cohesion for sexually abused students and non-abused students. Interpret.