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Old 07-28-2007   #1
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Default probability?

multiple choice questions each have five possible answers (a, b,c,d,e), one of which is correct. assume that you guess the answers to three such questions.use the multiplication rule to find the probability that the first two guesses are wrong and the third is correct. That is, find p(wwc), where c denotes a correct answer and w denotes a wrong answer?
Old 07-28-2007   #2
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4/5 * 4/5 * 1/5 = 16/125
Old 07-28-2007   #3
Mr. me
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The probability of a wrong answer is the number wrong over the total number of possible answers. Since, for each question, only one answer is correct, the probability of a wrong answer is 4/5, and the probability of a correct answer is 1/5Hence p(wwc) = 4/5 * 4/5 * 1/5 = 16/125 (or .128)
Old 07-28-2007   #4
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Probability is 0.128

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