Sample Size Determination for A Descriptive Study

Dear Stat Help,

I am putting together a consultancy proposal and in need of some guidance on calculating a sample size for a descriptive study.

Background: We want to do a diagnostic study of cooperatives. In total we are looking at 681 cooperatives. 234 are categorized as active and 447 are inactive. Both the active and inactive groups need to be interviewed. With a 95% confidence level and 5% margin error what formula should we use?

Any help will be appreciated.