Nationwide, the average waiting time until a electric utility customer service representative answers a call is 310 seconds. The Gigantic Kilowatt Energy Company
Randomly sampled 40 calls and found that, on average, they were answered in 287
Seconds with a population standard deviation of 30 seconds. Can the company claim that
They are faster than the average utility at α = 0.05?
A) Yes, because the test value -0.12 falls in the critical region.
B) Yes, because the test value -4.85 falls in the critical region.
C) No, because the test value -0.12 falls in the critical region.
D) No, because the test value -0.77 falls in the critical region.

Question

Quizplus · Accepted Answer

The correct answer is B because when conducting a hypothesis test to determine if the company's average call answer time is significantly lower than the national average, the test statistic calculated from the given data falls within the critical region for a significance level of α = 0.05, indicating that the company can claim to be faster. The test statistic is calculated using the formula for a z-test since the population standard deviation is known. The calculation would show a significant difference from the national average, leading to the conclusion in choice B.

Nationwide, the Average Waiting Time Until a Electric Utility Customer