In #29, we are supposed to recognize that p(1-p)/n is largest for p = 0.5. The standard error is then no larger than 0.5 / sqrt(n).
We want a 95% confidence interval of plus or minus 0.03. This means 1.96 x 0.5 / sqrt(n) = 0.03 or sqrt(n) = 1.96 x 0.5 / 0.03 = 32.6667. The required n is 1067.1111 or 1068 observations.
Posted by bparke at November 13, 2003 11:41 AM