# Z test

3. Jiffy lube advertises a 30 minute oil change. A sample of 35 customers showed a mean change time of 34 and a standard deviation of 8.3 minutes. Assuming normality, at the α = .05 level, is there enough evidence to show the mean oil change time is different?

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#### Solution Summary

The solution provides step-by-step method for the calculation of the Z-test statistic and P-value. Formula for the calculation and Interpretations of the results are also included in both doc and pdf format.

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