Question 549938
In a multiple-choice test, each question has four options. 
p(correct) = 1/4 ; p(incorrect) = 3/4
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Students will get 4 points for each correct answer; lose 1 point for each incorrect answer; and receive no points for unanswered questions. 
Random "gain" values: 4:::-1:::0
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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 

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E(x) = (1/4)4 + (3/4)(-1) + 0 = 1/4
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He should answer every question.
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Cheers,
Stan H.
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