Refer to Exercise 24.

a. Construct and interpret a 95% confidence interval for the difference between the true proportions. Assume that the conditions for inference are met.

b. Explain how the confidence interval provides more information than the test in Exercise 24.

Exercise 24.

Which of two widely prescribed drugs—Lipitor or Pravachol—helps lower “bad cholesterol” more? In an experiment, called the PROVE-IT Study, researchers recruited about 4000 people with heart disease as subjects. These volunteers were randomly assigned to one of two treatment groups: Lipitor or Pravachol. At the end of the study, researchers compared the proportion of subjects in each group who died, had a heart attack, or suffered other serious consequences within two years. For the 2063 subjects using Pravachol, the proportion was 0.263. For the 2099 subjects using Lipitor, the proportion was 0.224.15