it depends. i'm assuming you didn't buy feminized seeds. you can also look it up on the net or others may have ideas, but you can make your chances of making the seed a female. like putting a banana peel in a plastic bag with your seeds.... or something that has to do with birth control pills or blood. i swear i read that somewhere!!! LOL but i've done the banana thing and 2 out of 2 seeds have been girlies!!!

as for your question, it is hard to say how many would be female. because it also depends on if you put the plant through any kinds of stress during growing and that can change the sex of the plant as well.