statistics
posted by John .
Linda Silbers is a social scientist studying voter opinion about a city bond proposal for a light rail mass transit system in Denver
If Linda wants to be 90 percent Confident that her sample estimate of the proportion of voters who favor the bond is within 2 percent of the population percent p who favor the bond how large a sample should she use?

n=(z*/m)squared(p*)(1p*)
so be sure to square (z*/m)
m= margin of error, the invNorm for 90% is 1.645, p*=.5, if not given
The problem worked out:
(1.645/0.02)squared(.5)(1.5)= 1691.265625 so the sample size should be 1691 people. Hope this helps