Question 311675
To test the null hypothesis that the average lifetime for a particular brand of bulb is 700 hours versus the alternative that the average lifetime is different from 700 hours, a sample of 80 bulbs is used. 
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If the standard deviation is 40 hours and α is equal to 0.05, what values for x will result in rejection of the null hypothesis
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Ho: u = 700
Ha: u is not equal to 700
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You have to have the mean of a sample at this point of the problem solving.
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Cheers,
Stan H.