SOLUTION: Could someone please help me with this stats problem I do not understand it at all.. Thanks in advance. A researcher is interested in estimating the noise levels in decibels at

Question 674913: Could someone please help me with this stats problem I do not understand it at all.. Thanks in advance.
A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 99% confident that her estimate is correct.If the standard deviation is 4.09, how large a sample is needed to get the desired information to be accurate within 0.53 decibels? Show all work
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 99% confident that her estimate is correct.If the standard deviation is 4.09, how large a sample is needed to get the desired information to be accurate within 0.53 decibels?
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Since E = z*s/sqrt(n),
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n = [z*s/E]^2
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The z-value associated with 99% comfidence is invNorm(0.995) = 2.5758
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Your Problem:
n = [2.5758*4.09/0.53]^2 = 396 when rounded up.
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Cheers,
Stan H.
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