A researcher conducted a study that examined the proportion of high school students who cheated on tests at least twice during the past year. Included in that study were the results for both 2002 and 2004. A reported 9054 out of 24,142 students said they cheated at least twice in 2004. A reported 5784 out of 12,121 students said they cheated at least twice in 2002.
a. Provide an estimate for the difference between these two proportions.
b. Provide a 90% confidence interval for the difference between these two proportions.