A physical therapist wants to determine the difference in the proportion of men and women who participate in regular sustained physical activity. What sample size should be obtained if shewishes the estimate to be within twopercentage points with 90%confidence, assuming that
(a) sheuses the estimates of 21. 9%male and 18. 5%female from a previous year?
(b) shedoes not use any prior estimates?
A. N = ____
B. N = ____
