you missed the point. the problem is more like this:

1. Find the 30 best speakers that are available and can speak to a relevant/interesting topic to your event.

2. How many of them are men? How many are women?

3. If there are less than 15 women then it means that whatever metric you used to pick "best" didn't select a 1:1 ratio. Now you have to decide which do you consider more important, your "best" metric or 1:1 gender ratio?

4. If 1:1 gender ratio is more important than best than you have deliberately excluded male candidates for reasons that are fundamentally unfair to them.