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