Question 1102406
To get 60%, the person needs to get 12 answers correct(0.60 * 20)
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probability(p) of guessing correctly on a problem is 1/4 = 0.25
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we use the binomial probability formula
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Probability (k successes out of n trials) = nCk * p^k * (1-p)^(n-k), where p is probability of a success, nCk = n! / (k! * (n-k)!)
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for this problem n=20, k=12, p = 0.25
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P (12 successes out of 20 trials) = 20C12 * (0.25)^12 * (1-0.25)^(20-12) = 0.00075
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Probability of getting 60% on the quiz by guessing is 0.00075
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good reason to study  :-)
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