Steve wonders "Why don’t I have a girlfriend?" He uses the following information. There are 10,000 girls and women who live in his city, but only 5% of them are age-appropriate for him. A total of 50% have the required level of education, and he expects that 50% of the women in the selected group are attractive to him and he hopes that at least 20% will find him attractive too.

How many girls in his city are potential girlfriends?

Inspired by a scientific article by Peter Backus.