Question: Case Study #3:

Ohio State public health researcher wants to know how two high schools, one in the inner city and one in the suburbs, differ in the percentage of students who smoke. A random survey of students gives the following results:

Population n Smokers

1(inner-city) 250 200

2(suburban) 500 350

Question

a. What is a 90% confidence interval for the difference between the smoking rates in the two schools? (See Example on section “Univariate Inferential Tests” on pages 109 & 110) .