Question

What sample size would be needed to construct a 95% confidence interval with a 5% margin of error on any population proportion?

Give a whole number answer. (Of course.)

Answer 1

Solution :

Given that,

margin of error = E = 5% = 0.05

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 / 0.05)2 * 0.5 * 0.5

= 384.16

Sample size =384 rounded