Use the given data to find the minimum sample size required to estimate a population proportion or percentage. In a study of government financial aid for college students, it becomes necessary to estimate the percentage of full-time college students who earn a bachelor’s degree in four years or less.

a. Find the sample size needed to estimate that percentage. Use a 0.05 margin of error, and use a confidence level of 95%.

b. Assume that nothing is known about the percentage to be estimated.