Nationwide, the average waiting time until an electric utility customer service representative answers a call is 200 seconds per call. The Gigantic Kilowatt Energy Company took a sample of 40 calls and found
That, on the average, they answered in 140 seconds per call with a standard deviation of $30. Can the
Company claim that they are faster than the average utility?
A) Yes, because -12.65 falls in the critical region
B) No, because -2.00 falls in the critical region
C) Yes, because -0.32 falls in the noncritical region
D) No, because -0.32 falls in the critical region

Question

Quizplus · Accepted Answer

The test statistic is calculated as (140 - 200) / (30/√40) = -12.65, which falls in the critical region, allowing the company to claim they are faster.

Nationwide, the Average Waiting Time Until an Electric Utility Customer