Assume the U.S. president wants an estimate of proportion of population who support his current policy toward revisions in Social Security system. The president wants the estimate to be within 0.02 of the true proportion. Assume a 90 percent level of confidence. The president's political advisors estimated the proportion supporting the current policy to be 0.6. (Round up your answers to the next whole number.)
(a) How large of a sample is required? .
(b) How large of a sample would be necessary if no estimate were available for the proportion that support current policy?