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. Find the sample size needed to estimate that percentage. Use a 0.04 margin of error and use a confidence level of 95%. Complete parts (a) through (c) below.
a. Assume that nothing is known about the percentage to be estimated
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b. Assume prior studies have shown that about 40% of full-time students earn bachelor's degrees in four years or less.
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c. Does the added knowledge in part (b) have much of an effect on the sample size?​