You Are Interested in Determining the Average Cost of a 3-Minute

Multiple Choice

You are interested in determining the average cost of a 3-minute telephone call to locations within the continental U.S.What sample size must you take to be 96% confident that the results will be within $.75 of the true mean cost per call? From the phone company,you have gotten an estimate of $\text { ? }$
= 7.71.

A) 185
B) 445
C) 406
D) 574
E) 22