Question 234143: To test the null hypothesis that the average lifetime for a particular brand of bulb is 725 hours versus the alternative that the average lifetime is different from 725 hours, a sample of 90 bulbs is used. If the standard deviation is 75 hours and α is equal to 0.05, what values for will result in rejection of the null hypothesis (show all work).
Thanks for all your help!!
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! To test the null hypothesis that the average lifetime for a particular brand of bulb is 725 hours versus the alternative that the average lifetime is different from 725 hours, a sample of 90 bulbs is used.
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If the standard deviation is 75 hours and α is equal to 0.05, what values for will result in rejection of the null hypothesis (show all work).
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A two-tail test is implied.
The rejection interval is a function of alpha = 5% and the degrees of freedom.
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invT(0.025,89) = -1.0987
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The rejection interval is (-inf,-1.0987)U(1.0987,+inf)
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Cheers,
Stan H.
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