The mean number of travel days per year for salespeople employed by hardware distributors needs to be estimated with a 0.90 degree of confidence. For a small pilot study the mean was 150 days and the standard deviation was 14 days. If the population mean is estimated within two days, how many salespeople should be sampled?
A) 134
B) 452
C) 511
D) 2100

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 Salespeople