Question 905950

You may use Your TI (or any other calculator for the Arithmetic...)
this one is a need to know:  ME = {{{z*alpha/sqrt(n)}}} 0r ME = {{{z*sqrt(p(1-p)/n)}}} when You do not know{{{alpha}}}
ME = .07 = 1.96sqrt(.7*.3/n)
 (.07/1.96)^2  = .21/n
n = .21/(.07/1.96)^2 = 164.64  0r 165 (always round Up for number of people)