Question 464205
If the student guessed the answer for one question then the probability that she is correct is 1/5 or 0.2 . The probability that she is incorrect is 1-0.2 = 0.8. So the expected point if she guessed an answer is 0.2(5)-0.8(2)=-0.6. The expected point if she didn't answer the question is 0. Therefore it is to her disadvantage to guess an answer.