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 90% confident that the sample mean is correct to within $ 50 of the population mean annual family medical expenses. A previous study indicates that the standard deviation is approximately $252.

a. How large a sample is necessary?

n= ___

(Round up to the nearest integer.)

b. If management wants to be correct to within $25, how many employees need to be selected?

n= ___

(Round up to the nearest integer.)