The Mean Number of Travel Days Per Year for the Outside

Multiple Choice

The mean number of travel days per year for the outside salespeople employed by hardware distributors is to be estimated. The 0.90 degree of confidence is to be used. The mean of a small pilot study was 150 days, with a standard deviation of 14 days. If the population mean is to be estimated within two days, how many outside salespeople should be sampled?

A) 133
B) 452
C) 511
D) 2,100