Question 1086667: Nationwide, the average waiting time until a electric utility customer service representative answers a call is 210 seconds. The Gigantic Kilowatt Energy Company randomly sampled 30 calls and found that, on average, they were answered in 183 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 –4.93 falls in the critical region.
b. No, because the test value –0.90 falls in the critical region.
c. Yes, because the test value –0.16 falls in the critical region.
d. No, because the test value –0.16 falls in the critical region.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Nationwide, the average waiting time until a electric utility customer service representative answers a call is 210 seconds. The Gigantic Kilowatt Energy Company randomly sampled 30 calls and found that, on average, they were answered in 183 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?
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Ho: u >= 210
Ha: u < 210 (claim)
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z(183) = (183-210)/(30/sqrt(30)) = -4.93
Reject interval:: z < -1.96
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Conclusion:: Reject Ho
Conclusion:: Accept the claim
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Answer:
a. Yes, because the test value –4.93 falls in the critical region.
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Cheers,
Stan H.
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