Question

A 201Washington Post poll of 1001 adults found that 58% of those surveyed believe it should be legal for gays and lesbian couples to marry? Find the margin of error and the 95% confidence interval

Answer 1

Solution :

Given that,

n = 1001

Point estimate = sample proportion = = 0.58

1 - = 1-0.58=0.42

At 95% confidence level

= 1 - 95%  

= 1 - 0.95 =0.05

/2 = 0.025

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

Margin of error = E = Z / 2 * (( * (1 - )) / n)

= 1.96 (((0.58*0.42) / 1001)

E.=0.0306

Margin of error = E =0.0306