Question 459844
A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 95% confident that her estimate is correct. If the standard deviation is 4.02, how large a sample is needed to get the desired information to be accurate within 0.58 decibels? 
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n = [z*s/E]^2
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n = [1.96*4.02/0.58]^2 = 185 when rounded up
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Cheers,
Stan H.
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