SOLUTION: A doctor at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 95% confident that the true mean is wi

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Question 508813: A doctor at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 95% confident that the true mean is within 3 ounces of the sample mean? The standard deviation of the birth weights is known to be 7 ounces.
Answer by stanbon(75887) About Me  (Show Source):
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A doctor at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 95% confident that the true mean is within 3 ounces of the sample mean? The standard deviation of the birth weights is known to be 7 ounces.
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n = [z*s/E]^2
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n = [1.96*7/3]^2 = 21 when rounded up
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Cheers,
Stan H.
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