SOLUTION: Hi I am completely stumped on this one i can not for the life of me figure it out...I have seen some similar but not quite what i need ot figure this one out.....In a multiple-choi

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Question 464205: Hi I am completely stumped on this one i can not for the life of me figure it out...I have seen some similar but not quite what i need ot figure this one out.....In a multiple-choice test, each question has five options.Students will get 5 points for each correct answer; lose 2 ponts for each incorrect answer; and recieve no points for unanswered questions.A 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 reviewermath(1029) (Show Source):
You can put this solution on YOUR website!
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.