Significance for the mean lifetime of light bulbs

Reference no: EM13112150

A manufacturer claims that the mean lifetime, mu , of its light bulbs is 48 months. The standard deviation of these lifetimes is 9 months. Ten bulbs are selected at random, and their mean lifetime is found to be 51 months. Assume that the population is normally distributed. Can we conclude, at the 0.1 level of significance, that the mean lifetime of light bulbs made by this manufacturer differs from 48 months?

What is the critical value at .1 significance? Can we conclude the mean lifetime of light bulbs made by this manufacturer differs from 48 months?

Reference no: EM13112150

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