A television sports commentator desires to determine the proportion of citizens who "follow professional football." Complete parts (a) through (c). What sample size should be obtained if he wants to be within 4 percentage points with 96% confidence if he uses an estimate of 48% obtained from a poll? What sample size should be obtained if he wants to be within 4 percentage points with 96% confidence if he does not use any prior estimates? Why are the results from parts (a) and (b) so close?