5.72. For a random sample of n subjects, explain why it is about 95% likely that the sample proportion has error no more than 1/ in estimating the population proportion. {Hint: To show this "1/Jli Rule," find two standard errors when tt = 0.50, and explain how this compares to two standard errors at other values oftt.) Using this result, show that n = l/M2 is a safe sample size for estimating a proportion to within M with 95% confidence.