An epidemiologic study examined risk factors associated with pediatric AIDS. In a small study of 30 cases and 30 controls, a positive history of substance abuse occurred among 11 of the cases and 6 of the controls. Based on these data, can the investigator assert that substance abuse is significantly associated with pediatric AIDS at the a = 0.05 level? Compute the approximate 95% confidence interval for the difference between the proportions of substance abuse found in the case and control groups.