<PRE><B>Question 421429</B>
In a multiple-choice test, each question has five options. 
Students will get 10 points for each correct answer; lose 2 point for each incorrect answer; and receive no points for unanswered questions. 
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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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Random Values: 10 ; -2, ; 0
Probabilities: 1/4; 4/5 ; 0
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E(x) = (1/5)10 - (4/5)2
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E(x) = 2 - 8/5
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E(x) = 10/5 - 8/5 = 2/5 = 0.4
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She should guess
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Cheers,
Stan H.
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