SOLUTION: A study of the amount of time it takes a mechanic to rebuild the transmission of a 1992 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 2.4 hours.

Question 187100: A study of the amount of time it takes a mechanic to rebuild the transmission of a 1992 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 2.4 hours. If 36 mechanics are randomly selected, find the probability that their mean rebuild time is more than 8.8 hours.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A study of the amount of time it takes a mechanic to rebuild the transmission of a 1992 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 2.4 hours. If 36 mechanics are randomly selected, find the probability that their mean rebuild time is more than 8.8 hours.
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The distribution of all the sample means of sample size 36 is
u of sample means = 8.4
s of the sample means is 2.4/sqrt(36) = 2.4/6 = 0.4
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z(8.8) = (8.8-8.4)/(0.4) = 0.4/0.4 = 1
P(a sample mean is > 8.8 = P(z > 1) = 0.1587
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Cheers,
Stan H.
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