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Hypothesis Testing: What is the mean life for a shipment of lightbulbs?

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The quality-control manager at a light bulb factory needs to determine whether the mean life of a large shipment of light bulbs is equal to 375 hours. The population standard deviation is 100 hours. A random sample of 64 light bulbs indicates a sample mean life of 350 hours.
a. At the 0.05 level of significance, is there evidence that the mean life is different from 375 hours?
b. Compute the p-value and interpret its meaning.

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Solution Summary

The solution provides step by step method for the calculation of testing of hypothesis. Formula for the calculation and interpretations of the results are also included in an attached Word document. An interactive Excel sheet is included. The user can edit the inputs and obtain the complete results for a new set of data.

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3. The quality-control manager at a light bulb factory needs to determine whether the mean life of a large shipment of light bulbs is equal to 375 hours. The population standard deviation is 100 hours. A random sample of 64 light bulbs indicates a sample mean life of 350 hours.
Answers
a. At the 0.05 level of significance, is there evidence that the mean life is different from 375 hours?
The null hypothesis tested is
H0: Mean life of light bulbs = 375 hours. (µ = 375)
The alternative hypothesis is
H1: Mean life of light bulbs ≠ ...

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