SOLUTION: 40 multiple choice questions, 4 possible answers for each question, only one correct answer, if random guesses for all questions, what is the mean and standard deviation for number

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Question 677849: 40 multiple choice questions, 4 possible answers for each question, only one correct answer, if random guesses for all questions, what is the mean and standard deviation for number of correct answers?
Answer by stanbon(75887) About Me  (Show Source):
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40 multiple choice questions, 4 possible answers for each question, only one correct answer, if random guesses for all questions, what is the mean and standard deviation for number of correct answers?
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mean = np = 40*(1/4) = 10
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std = sqrt(npq) = sqrt(10*(3/4) = sqrt(7.5) = 2.7386
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cheers,
Stan H.