In a study of 424 nonprofits nationwide, 80 indicated that turnover has been the biggest employment challenge at their organization. Complete parts a) and b).

a) Construct a 95% confidence interval for the population proportion of nonprofits that indicate turnover as the biggest employment challenge at their organization.

b) If you wanted to conduct a follow-up study to estimate the population proportion of nonprofits that indicate turnover as the biggest employment challenge at their organization to within plus or minus 0.03 with 95 % confidence, how many nonprofits would you survey?