SOLUTION: An automotive repair shop has determined that the average service time on an automobile is 130 minutes with a standard deviation of 26 minutes. A random sample of 40 automotive ser
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Question 359609: An automotive repair shop has determined that the average service time on an automobile is 130 minutes with a standard deviation of 26 minutes. A random sample of 40 automotive services is selected.
a. Compute the standard error of the mean.
b. What is the probability that the sample of 40 automotive services will have a mean service time greater than 136 minutes?
c. Assume the population consists of 400 automotive services. Determine the standard error of the mean.
You can put this solution on YOUR website! An automotive repair shop has determined that the average service time on an automobile is 130 minutes with a standard deviation of 26 minutes. A random sample of 40 automotive services is selected.
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a. Compute the standard error of the mean.
SE = s/sqrt(n) = 26/sqrt(40) = 4.11
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b. What is the probability that the sample of 40 automotive services will have a mean service time greater than 136 minutes?
t(136) = (136-130)/4.11 = 1.4595
P(x-bar >= 136) = P(t >= 1.4595 with df = 39) = 0.0762
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c. Assume the population consists of 400 automotive services. Determine the standard error of the mean.
SE = 26/sqrt(400) = 1.3
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Cheers,
Stan H.
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