Question 271204: To test the null hypothesis that the average lifetime for a particular brand of bulb is 750 hours versus the alternative that the average lifetime is different from 750 hours, a sample of 75 bulbs is used. If the standard deviation is 50 hours and a is equal to 0.01, what values for will result in rejection of the null hypothesis. Remember to determine whether this is a one- or two-tailed test. (Hint: This is similar to problem #4 but it is NOT a one-tailed test!)
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 750 hours versus the alternative that the average lifetime is different from 750 hours, a sample of 75 bulbs is used.
If the standard deviation is 50 hours and a is equal to 0.01, what values for will result in rejection of the null hypothesis. Remember to determine whether this is a one- or two-tailed test.
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Ho: u = 750
Ha: u is not equal to 750 (2-tail test)
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Critical values for 2-tail, with alpha = 1% and df = 74:
Using a TI-84 calculator I get invT(0.005,74) = +-2.6439
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The rejection intervals are t<-2.6439 and t>2.6439
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Cheers,
Stan H.
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