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 +$75 of the population mean annual family medical expenses. A previous study indicates that the standard deviation is approximately $349. a. How large a sample is necessary? b. If management wants to be correct to within +$30, how many employees need to be selected? Click here to view page 1 of the cumulative standardized normal distribution table. Click here to view page 2 of the cumulative standardized normal distribution table. a. How large a sample is necessary? n= (Round up to the nearest integer.) b. If management wants to be correct to within + $30, how many employees need to be selected? n= (Round up to the nearest integer.)