A survey is planned to determine the mean annual family medical expenses of employees of a large company. The management of the company wishes to be 95% confidant that the sample mean is correct to within +-$ 50 of the population mean annual family medical expenses
A previous study indicates that the SD is app. $400
a.How large a sample is necessary?
b.If management wants to be correct to within +- $25, how many employees need to be selected