Nevermind that the gouge is not considered "cheating." You're expected to have done your homework preparing for the interview and can expect to be asked what kind of preparation work you have done. I did a whole lot of studying... but I also was sure to review the gouge to get an idea of what to expect. It's not like the gouge gave me specific answers to any written questions, although it did prepare me for how some were setup and ensured I knew how to arrive at the correct answer.

Don't try to rehearse or memorize answers. Practice how you're going to arrive at them.