Posted by Blegh on Saturday, November 3, 2012 at 2:29pm.
We guess, based on historical data, that 30% of graduating highschool seniors in a large city will have completed a firstyear calculus course. What's the minimum sample size needed to construct a 95% confidence interval for a proportion with a margin of error of 2.5%?
1537
1291
1286
1533
1223

AP Statistics  MathGuru, Saturday, November 3, 2012 at 6:16pm
Formula to find sample size:
n = [(zvalue)^2 * p * q]/E^2
... where n = sample size, zvalue is found using a ztable for 95% confidence (which will be 1.96), p = .30, q = 1  p, ^2 means squared, * means to multiply, and E = .025 (2.5%)
Convert all fractions to decimals, then plug values into the formula and calculate n. Round your answer to the next highest whole number.

AP Statistics  Jessica, Monday, April 8, 2013 at 8:08pm
1533
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