Question

Suppose a marketing company wants to determine the current proportion of customers who click on ads on their smartphones. It was estimated that the current proportion of customers who click on ads on their smartphones is 0.68. How many customers should the company survey in order to be 92% confident that the margin of error is 0.21 for the confidence interval of true proportion of customers who click on ads on their smartphones?

Answer 1

Solution :

Given that,

= 0.68

1 - = 1 - 0.68 = 0.32

margin of error = E = 0.21

At 92% confidence level the z is ,

= 1 - 92% = 1 - 0.92 = 0.08

/ 2 = 0.08 / 2 = 0.04

Z_/2 = Z_0.04 = 1.751

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

= (1.751 / 0.21)² * 0.68 * 0.32

= 15.1 = 15

Answer = 15