Question 451261
What is the sample size needed to be able to estimate the mean dollars that each card holder will spend each month. It would like to be within plus or minus $25 of the true mean with a 98% confidence level.  The standard deviation is thought to be $400. How many card holders should be sampled?
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n = [z*s/E]^2
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n = [2.3263*400/25]^2 = 347 when rounded up
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Cheers,
Stan H.
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