Question

A mobile phone marketing company wants to survey a sample to estimate the true proportion of all cell phone users that play games on their phone. There is an old survey which showed that 61% of the cell phone users played games on the phone. What is the minimum number of cell phone users needed in the new survey to be 95% confident and with a margin of error 0f .02

Answer 1

Solution :

Given that,

= 0.61

1 - = 1 - 0.61 = 0.39

margin of error = E =0.02

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 / 0.02)2 * 0.61 * 0.39

= 2284.79

Sample size =2285