A large electronics company wants to estimate the proportion of all households that own GPS machines. What sample size is required that would give the maximum error of 2.0% for a 95% confidence interval? An unscentific survey had an inital result of 30% .

Question

A large electronics company wants to estimate the proportion of all households that own GPS machines. What sample size is required that would give the maximum error of 2.0% for a 95% confidence interval? An unscentific survey had an inital result of 30% .

Answer 1

Formula to find sample size:

n = [(z-value)^2 * p * q]/E^2
... where n = sample size, z-value is found using a z-table for 95% confidence (which is 1.96), p = .3, q = 1 - p, ^2 means squared, * means to multiply, and E = .02.

Plug values into the formula and calculate n.

I hope this will help get you started.