# Null Hypothesis/ Two Tailed Test

Problem (two tailed test)

A manufacturer claims that the mean lifetime, mu, of its light bulbs is 44 months. The standard deviation of these lifetimes is 7 months. Seventy bulbs are selected at random, and their mean lifetime is found to be 43 months. Can we conclude, at the 0.1 level of significance, that the mean lifetime of light bulbs made by this manufacturer differs from 44 months?

Question

-H0 (null hypothesis):

-H1 (alternative hypothesis):

-Type of test statistic: (Z, t, F, chi squared)

-The value of the test statistic (round to at least 3 decimal places):

-The two critical values at the 0.1 level of significance (round to at least 3 decimal places): ___ and ___

-Can we conclude that the mean lifetime of light bulbs made by this manufacturer differs from 44 months? (yes, no)

https://brainmass.com/statistics/hypothesis-testing/null-hypothesis-two-tailed-test-141057

#### Solution Preview

Problem (two tailed test)

A manufacturer claims that the mean lifetime, mu, of its light bulbs is 44 months. The standard deviation of these lifetimes is 7 months. Seventy bulbs are selected at random, and their mean lifetime is found to be 43 months. Can we conclude, at ...

#### Solution Summary

The solution performs a hypothesis test for a manufacturer for light bulbs.