SOLUTION: A researcher wishes to estimate the number of households with two computers. How large a sample is needed in order to be 95% confident that the sample proportion will not differ fr

Question 866641: A researcher wishes to estimate the number of households with two computers. How large a sample is needed in order to be 95% confident that the sample proportion will not differ from the true proportion by more than 5%? A previous study indicates that the proportion of households with 2 computers is 21%.
A) 5
B) 180
C) 323
D) 255
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A researcher wishes to estimate the number of households with two computers. How large a sample is needed in order to be 95% confident that the sample proportion will not differ from the true proportion by more than 5%? A previous study indicates that the proportion of households with 2 computers is 21%.
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E = zsqrt(pq/n)
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n = [z/E]^2*pq
n = [1.96/0.05]^2*0.21*0.79 = 255 when rounded up
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A) 5
B) 180
C) 323
D) 255

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