It was a great question in terms of something you might work through in classroom setting for advanced undergraduates or beyond. I thought it was really interesting. However, I think the weakness of it would be that anyone with a particular background (out-of-core) would identify it immediately. Many of the "hard questions" really come down to being some shibboleth to identify who has been at the right schools. :-) (and that's not a particularly sour note from me, as I have a CMU PhD, although I still can't get those questions)