Need help in knowing how to start this one: A researcher…

Question

A researcher would like to estimate the proportion of home-based businesses owned by women. What is the minimum sample size needed to be 99% confident with a 3.9% margin of error? (Round your answer to the appropriate integer) 

Answer: n = _____

(Where do I start with this question?)

Answer 1

sample size (n) = phat * (1-phat) * (z alpha/2 /E)^2

where z alpha/2 = critical z for 99% confidence interval = 2.575,

E given as 0.039 (3.9% in decimal) and

since phat is not given, we assume it is 0.5, so plugging the numbers into the formula:

n = 0.5 * (1-0.5) * (2.575/0.039)^2 = 1089.84 ~ 1090