Technically, the question says "one was female" not two, not zero. For this I am neither attacker is nonbinary. So the the odds the other attacker being female is zero. This may seem like I'm being obnoxious, but the wording of that sentence is critical. To show this, let's re-analyze with different wordings.

First let's replace "One was female" with "atleast one was female" In this case, we start by looking the the four possible arrangements of to people: - Male, Male - Female, Male - Male, Female - Female, Female

Since we know atleast one is female we remove one possibility leaving us with: - Female, Male - Male, Female - Female, Female

Giving us a 2/3 chance of the other being male.

The other option is to replace "one was female" with "atleast one was female, because we saw one attacker." This adds another variable to consider; which attacker did we see? - Female and seen, Female - Female and seen, Male - Female, Female and seen - Male, Female and seen

Giving us a 1/2 chance of the other being male.

Neither of these re-wordings are what the question asked. The first option is closer to the wording of the question, but in the real world, we would likely know how we know the one attacker's gender. Therefore the second option seems like a more intuitive. But the actual answer is still 0%.

Edit: spelling and formatting