<PRE><B>Question 402584</B>
A random sample of medical files is used to estimate the proportion p of all people who have blood type B. If you have no preliminary estimate for p, how many medical files should you include in a random sample in order to be 85% sure that the point estimate will be within a distance of 0.1 from p
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Since ME = z*sqrt(pq/n)
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n = [z/E]^2*pq
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Your Problem:
n = [1.440/0.1]^2*(1/2)(1/2)
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n = 207.35*(1/4)
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n = 52 when rounded up
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Cheers,
Stan H.</PRE>