Plainfield Telemarketing Plans to Estimate the Average Number of Telephone

Multiple Choice

Plainfield Telemarketing plans to estimate the average number of telephone contacts made by its 245 sales reps over the past month.A sample of reps will be randomly selected for the estimate.To construct a 99% confidence interval estimate in which the margin of error will be no more than 20 contacts, how many reps should be included in the sample? Assume a similar study showed a standard deviation of 120 contacts.

A) 268
B) 145
C) 169
D) 121
E) 240