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) 134
B) 452
C) 511
D) 2,100
E) None of the choices are correct

Question

Quizplus · Accepted Answer

The sample size needed to estimate the population mean within two days with a 0.90 degree of confidence is 511. This is calculated using the formula: n = (Z^2 * s^2) / E^2, where Z is the z-score for the desired confidence level, s is the sample standard deviation, and E is the margin of error. In this case, Z = 1.645 (for a 0.90 confidence level), s = 14, and E = 2. Plugging these values into the formula, we get n = (1.645^2 * 14^2) / 2^2 = 511.

The Mean Number of Travel Days Per Year for the Outside