Introduction to statistics
posted by Elizabeth .
A researcher would like to estimate the population proportion of adults living in a certain town who have at least a high school education. No information is available about its value. How large a sample size is needed to estimate it to within 0.19 with 99% confidence?
n=
(Round up to the nearest integer)

Formula to find sample size:
n = [(zvalue)^2 * p * q]/E^2
... where n = sample size, zvalue is found using a ztable for 99% confidence, p = .50 (when no value is stated in the problem), q = 1  p, ^2 means squared, * means to multiply, and E = 0.19.
Plug values into the formula and calculate n.
I hope this will help get you started.