Suppose that you live near a McDonald's restaurant and you want to estimate the proportion of all people in your neighborhood who go to McDonald's on a typical day. 

a. If you had no preliminary estimate for p , how many people should you include in a random sample to be 95% sure that the point estimate p will be within a distance of 0.05 from p? 

b. Answer part a if you use the preliminary estimate that nationally about 1 in 20 Americans goes to McDonald's every day.