# The quality control manager at a light bulb factory needs to estimate the mean life of a

## Question:

a. Construct a 95% confidence interval estimate for the population mean life of light bulbs in this shipment.

b. Do you think that the manufacturer has the right to state that the light bulbs have a mean life of 400 hours? Explain.

c. Must you assume that the population light bulb life is normally distributed? Explain.

d. Suppose that the standard deviation changes to 80 hours. What are your answers in (a) and (b)?

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**Related Book For**

## Basic Business Statistics Concepts And Applications

**ISBN:** 9780132168380

12th Edition

**Authors:** Mark L. Berenson, David M. Levine, Timothy C. Krehbiel