Nationwide, the average waiting time until a electric utility customer service r

Question

Nationwide, the average waiting time until a electric utility customer service representative answers a call is 200 seconds per call. The Gigantic Kilowatt Energy Company took a sample of 30 calls and found that, on the average, they answered in 120 seconds per call. Moreover, it is know that the standard deviation of the times for all such calls is 25 seconds At the.05 significance level, is there evidence that this company's mean response time is lower than the average utility? Yes, because -17.53 falls in the critical region No, because -3.20 falls in the critical region Yes, because -0.58 falls in the noncritical region No, because -0.58 falls in the critical region

Explanation / Answer

Test Statistic

z =((120-200)/25)*SQRT(30)

z = -17.53

So, Option A is Correct as -17.53 fall in the critical region

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