<PRE><B>Question 450489</B>
A private opinion poll is conducted for a politician to determine what proportion of the population favors adding more national parks. How large a sample is needed in order to be 99% confident that the sample proportion will not differ from the true proportion by more then 5%
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n = [z/E]^2*(pq)
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Use p = 1/2 = q as the least biased estimate of p.
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n = [2.5758/0.05]^2*(0.5)^2 
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= 664 when rounded up
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Cheers,
Stan H.
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