SOLUTION: I am not sure how to solve this problem. For their total production of light bulbs, the management of an electronics firm knows that the mean equals 150 hours. How large a sample

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Question 366920: I am not sure how to solve this problem.
For their total production of light bulbs, the management of an electronics firm knows that the mean equals 150 hours. How large a sample is needed if they want to be 90% confident that the estimate of the average production time will be within 30 hours of the correct value? Does this have something to do with margin of error?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
For their total production of light bulbs, the management of an electronics firm knows that the mean equals 150 hours. How large a sample is needed if they want to be 90% confident that the estimate of the average production time will be within 30 hours of the correct value? Does this have something to do with margin of error?
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Yes.
Since ME = z
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sqrt(n) = z*s/ME
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n = [zs/ME]^2
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Your Problem:
n = [1.645s/30]^2 where s is the standard deviation of the population.
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Cheers,
Stan H.
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