It is interesting; disregarding nitpicking about the calculation there could be multiple potential reasons that all are connected to the heart of the matter: -

It is interesting; disregarding nitpicking about the calculation there could be multiple potential reasons that all are connected to the heart of the matter: - women more likely to study and solve logistical study problems together - men more likely to pirate books - men less likely to be out during normal hours - men less likely to choose majors requiring library books - and of course, higher college enrollment by women I am not saying any of these were necessarily in play in your situation, but some probably are and colleges and employers should be thinking about them.