In a multiple choice question there are six options numbered 1, 2, 3, 4, 5, 6. Only two of these are the correct answer. Guessing only one correct answer rewards half credit. What is the probability that a student will get half credit?
I'll give this a shot.....
We have C(6,2) = 15 possible pairs of answers
For 1/2 credit, each of the correct answers will be paired 4 times with incorrect answers = 8 pairs
So .... P(1/2 credit) = 8 / 15 ≈ 53.3%
+77 
