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# Performing a one-tailed test

An automobile assembly line operation has a scheduled mean completion time, mean, of 14.7 minutes. The standard deviation of completion times is 1.2 minutes. It is claimed that, under new management, the mean completion time has decreased. To test this claim, a random sample of 60 completion times under new management was taken. The sample had a mean of 14.6 minutes. Assume that the population is normally distributed.

Perform a one-tailed test.
null H0:
alternative H1:
This is a z test
The value of the test statistic is
The critical value at the 0.01 level of significance: (round to at least three decimal places)
Can we support the claim that the mean completion time has decreased under new management?

#### Solution Preview

An automobile assembly line operation has a scheduled mean completion time, mean, of 14.7 minutes. The standard deviation of completion times is 1.2 minutes. It is claimed that, under new management, the mean completion time has decreased. To test this claim, a random sample of 60 completion times under new management was taken. The sample had a mean of 14.6 ...

#### Solution Summary

This solution contains a detailed explanation of how to perform a one-tailed test by the five-step procedure.

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