SOLUTION: In a multiple-choice test, each question has four options. Students will get 5 points for each correct answer; lose 1 point for each incorrect answer; and receive no points for un

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Question 363334: In a multiple-choice test, each question has four options. Students will get 5 points for each correct answer; lose 1 point for each incorrect answer; and receive no points for unanswered questions. A student does not know the correct answer for one question. Is it to her advantage or disadvantage to guess an answer? Show your calculations for expected value. Show your work for full credit.

Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
The probability of giving a correct answer is 1/4, the probability for a wrong answer is 3/4. If he has to give an answer, his expectation is 5%2A%281%2F4%29%2B%28-1%29%2A%283%2F4%29+=+5%2F4+-+3%2F4+=+2%2F4+=+1%2F2. If he doesn't give an answer, his expectation is 0. Therefore it is better to just guess the answer. =)