# SOLUTION: A math student guesses all the answers on a 15 question quiz. Assuming that the student guesses correctly 57% on each item, what is the probability of getting at most 8 answers

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 Question 426693: A math student guesses all the answers on a 15 question quiz. Assuming that the student guesses correctly 57% on each item, what is the probability of getting at most 8 answers correct on the quiz? Answer by ewatrrr(10682)   (Show Source): You can put this solution on YOUR website! ``` Hi Note: The probability of x successes in n trials is: P = nCx* where p and q are the probabilities of success and failure respectively. In this case p = .57 and q =.43 nCx = P(getting at most 8 answers correct out of 15 questions) 1 - P(9) - P(10) - P(11) - P(12) - P(13) - p(14) - P(15) = .4847 P(9) = 5005(.57)^9(.43)^6 for example would be P( 9 out of 15 correct) P(9) = 5005(.57)^9(.43)^6 = .20095 1 - .20095 - - - - etc = .4847 Note: one may using a Binomial Distribution Calculator P(x ≤ 8) ```