<PRE><B>Question 366222</B>
A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 90% confident that her estimate is correct. If the standard deviation is 4.13, how large a sample is needed to get the desired information to be accurate within 0.68 decibels?
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Since E = zs/sqrt(n),
n = [zs/E]^2
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n = [1.645*4.13/0.68]^2
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n = 100 when rounded up
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Cheers,
Stan H.
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