Legalize Marijuana Part II As discussed in Exercise 612 the

Legalize Marijuana, Part II

As discussed in Exercise 6.12, the 2010 General Social Survey reported a sample where about 48% of US residents thought marijuana should be made legal. If we wanted to limit the margin of error of a 95% confidence interval to 2%, about how many Americans would we need to survey?

Solution

Compute Sample Size ( n ) = n=(Z/E)^2*p*(1-p)
Z a/2 at 0.05 is = 1.96
Samle Proportion = 0.48
ME = 0.02
n = ( 1.96 / 0.02 )^2 * 0.48*0.52
= 2397.1584 ~ 2398