Question

What is the minimal sample size needed for a 95% confidence interval to have a maximal margin of error of 0.02 if there is no preliminary estimate for p?

A. 4161

B. 2401

C. 25

D. 1455

1455

Answer 1

Solution,

Given that,

= 0.5

1 - = 0.5

margin of error = E = 0.02

At 95% confidence level

= 1 - 95%  

= 1 - 0.95 =0.05

/2 = 0.025

Z/2 = Z0.025  = 1.96

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

= (1.96 / 0.02)2 * 0.5 * 0.5

= 2401

sample size = n = 2401

Correct option ;- 2401