The first page of the test was a fairly simple question which was worth 5 points. Both of the students answered it perfectly, and were sure the test would be easy. As they turned the second page they read “Question 2 (95 Points): Which Tire?”.
What if they got it right? That wouldn't be very fair to the other students.
There is a 25% chance they'll get it right... plus, we also have to factor in the possibility that they may have talked about their story before-hand and picked which tire "went flat". The teacher's methods seem rather flawed.