Author Question: You are interested in determining the average cost of a 3-minute telephone call to locations within ... (Read 74 times)

lunatika · **on:** Jun 24, 2018

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 = 7.71.
a. 185
b. 445
c. 406
d. 574
e. 22

Question 2

The lower limit of a confidence interval at the 95 level of confidence for the population proportion if a sample of size 200 had 40 successes is:
a. 0.2554.
b. 0.1446.
c. 0.2465.
d. 0.1535.