In a multiple-choice test, each question has five options. Students will get 5 points for each correct answer; lose 2 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.
If it is a sheer guess, the students have 4/5 chance of losing 2 points and 1/5 chance of gaining 5. Not answering is certain to get 0 points.
Does that help?posted by PsyDAG
yes thank you.posted by Jen