APFIVE Margin of Error for Difference in Proportions
Two independent random samples were taken to estimate the difference in the proportion of voters supporting a candidate in two districts. If n1 = 400, n2 = 600, and we want 95% confidence that our estimate is within 0.04 of the true difference, what must be true about p1 and p2?
A
p1 - p2 ≤ 0.04
B
p1(1-p1)/400 + p2(1-p2)/600 ≤ 0.04
C
p1(1-p1)/400 + p2(1-p2)/600 ≤ 0.0004
D
p1(1-p1) + p2(1-p2) ≤ 0.0004
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