Question: Are Seat Belts Effective?

Use the sample data in Exercise 15 with a 0.05 significance level to test the claim that the fatality rate is higher for those not wearing seat belts.

Sample: A simple random sample of front-seat occupants involved in car crashes is obtained. Among 2823 occupants not wearing seat belts, 31 were killed. Among 7765 occupants wearing seat belts, 16 were killed (based on data from “Who Wants Airbags?” by Meyer and Finney, Chance, Vol. 18, No.2). Constructs a 90% confidence interval estimate of the difference between the fatality rates for those not wearing seat belts and those wearing seat belts. What does the result suggest about the effectiveness of seat belts?