Question

Verizon Wireless is interested in conducting a study to determine the percentage of all their subscribers would be willing to pay $90 per month for totally unlimited national cell phone service. What is the minimum size sample needed to estimate the population proportion with a margin of error of 0.03 or less at 96% confidence?

Answer 1

Solution :

Given that,

= 1 - = 0.5

margin of error = E = 0.03

  At 96% confidence level the z is,

= 1 - 96%

= 1 - 0.96 = 0.04

/2  = 0.02

Z_/2 = Z _0.02 = 2.054

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

= ( 2.054 / 0.03 )² * 0.5 * 0.5

= 1171.92

sample size = n = 1172