For Exercises 8.49 to 8.51, see page 437; for 8.52 and 8.53, see pages 439–440; for 8.54 to 8.56, see page 440; for 8.57 to 8.58, see page 444; for 8.59, see page 445; and for 8.60, see page 447.

Question 8.56

8.56 Gender and commercial preference.

Refer to Exercises 8.52 and 8.53, where you analyzed data about gender and the preference for one of two commercials. The study also asked the same subjects to give a preference for two other commercials, C and D. Suppose that 92 women preferred Commercial C and that 120 men preferred Commercial C.

  1. The confidence interval for comparing two proportions should not be used for these data. Why?
  2. Compute the plus four confidence interval for the difference in proportions.