According to a study released by The Financial Brand, an online publication focusing on branding issues and advice affecting retail banks and credit unions, 68% of financial institutions use churn rate (attrition) to gauge the effectiveness of their marketing efforts.

a. If you conduct a follow- up study to estimate the population proportion of financial institutions that use churn rate to gauge the effectiveness of their marketing efforts, would you use a p of 0.68 or 0.50 in the sample size formula?

b. Using your answer in (a), find the sample size necessary to estimate, with 95% confidence, the population proportion to within ± 0.03.