I don't think there were more than 25 boys there when they got there -- and I mean in the room; some of them left or went to bed before she even started.
Then some more left; I bet there weren't ten guys there when it was over.
I would like to know why she left her cell, ID and make-up bag in the house. And her cash. Of course, Ted on Greta says it's proof positive that she was raped. I think she was just too drunk to notice...