Question

A politician wants to poll her constituents to determine their support for government-subsidized pre-Kindergarten. If she wants a 4% margin of error at 95% confidence, how many constituents must she poll?

Answer 1

Solution :

Given that,

= 0.5

1 - = 1 - 0.5 = 0.5

margin of error = E = 4% = 0.04

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z/2 = Z0.025= 1.96 ( Using z table )

Sample size = n = (Z/2 / E)2 * * (1 - )

= (1.96 / 0.04)2 * 0.5 * 0.5

= 600.25

Sample size =600