Confidence a a/2 Z a/2 Test Statistic: z = level p-Po 90% .1 .05 1.645 95% .05 .025 1.960 where: Op Po (1-Po) = n 99% .01 .005 2.576 assuming np > 5 and n(1 - p) 5 Interval Estimate of x 2/2 J S Test Statistics xta/2] n *- Necessary Sample Size Confidence Interval Pop. proportion z = |p(1 - p) /n pza/2 n n = (20/2)202 n = E2 (za/2)p(1 - p) E2 "