Question 83910: please help me with this statistical problem. An automobile assembly line operation has a scheduled mean completion time,u , of 13.4 minutes. The standard deviation of completion times is 1.7 minutes. It is claimed that, under new management, the mean completion time has decreased. To test this claim, a random sample of 90 completion times under new management was taken. The sample had a mean of 13.3 minutes. Can we support, at the 0.005 level of significance, the claim that the mean completion time has decreased under new management? Assume that the standard deviation of completion times has not changed.
Perform a one-tailed test.
Thanks!
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! An automobile assembly line operation has a scheduled mean completion time,u , of 13.4 minutes. The standard deviation of completion times is 1.7 minutes. It is claimed that, under new management, the mean completion time has decreased. To test this claim, a random sample of 90 completion times under new management was taken. The sample had a mean of 13.3 minutes. Can we support, at the 0.005 level of significance, the claim that the mean completion time has decreased under new management? Assume that the standard deviation of completion times has not changed.
Perform a one-tailed test.
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Ho: mu = 13.4
Ha: mu < 13.4
Critical value: z= -1.645
Test Statistic: z(13.3) = [13.3-13.4]/(1.7/sqrt90) = -0.5580
p-value = 0.288
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Conclusion: Fail to Reject Ho because p-value > alpha = 5%
mu = 13.4
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Cheers,
Stan H.
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