A smart guesser could do significantly better. The correct answer to multiple choice math problems is often surrounded on either side by decoys, an answer way out in left field, and the idiot trap "none of the above". For example if the answers are 23, 25, 27, 294, none, choosing the middle value 25 is the correct answer about half the time.
I was always able to narrow it down to two if I didn’t know the answer outright. You could usually eliminate one or two grammatically without knowing anything about the subject matter.