University final examination

[funmonger]

The blonde reported for her University final examination which consists of "yes/no" type questions. She takes her seat in the examination hall, stares at the question paper for five minutes, and then in a fit of inspiration takes her purse out, removes a coin and starts tossing the coin and marking the answer sheet - Yes for Heads and No for Tails.
Within half an hour she is all done whereas the rest of the class is sweating it out.
During the last few minutes, she is seen desperately throwing the coin, swearing and sweating.
The moderator, alarmed, approaches her and asks what is going on.
"I finished the exam in half and hour. But I'm rechecking my answers."