Question 451476
You want to estimate the mean repair cost for dishwashers. The estimate must be within $10 of the population mean. Determine the required sample size to construct 99% confidence interval for the population mean. Assume the population standard deviation is $22.50.
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n = [z*s/E]^2
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n = [2.5758*22.5/10]^2 = 34 when rounded up
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Cheers,
Stan H.