for the political approval example , what sample size was necessary to ensure the 95% confidence and margin or error of 0.03?

Political Approval Polling agencies often ask voters whether they approve or disapprove of the job a politician is doing. Suppose that pollsters want to estimate the proportion who approve of the job done by a particular politician to within 13% with 95% confidence. How large a sample should they take? . Want 95% ME of 0.03 . No information on p, so use p=0.5 . Formula: n~ 1/(0.03)2=1111.11 . Need to sample n=1112 voters