Question 669059: An instructor gives his class a set of 19 problems with the information that the next quiz will consist of a random selection of 9 of them. If a student has figured out how to do 12 of the problems, what is the probability the he or she will answer correctly
(a) all 9 problems?
(b) at least 8 problems?
Thank you for your time.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! An instructor gives his class a set of 19 problems with the information that the next quiz will consist of a random selection of 9 of them. If a student has figured out how to do 12 of the problems, what is the probability the he or she will answer correctly
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Binomial Problem with n= 19 ; p(correct) = 12/19 ; p(wrong) = 7/19
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(a) all 9 problems?
P(x = 9) = 19C9(12/19)^9*(7/19)^10 = binompdf(19,12/19,9) = 0.0681
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(b) at least 8 problems?
P(8<= x <=19) = 1 - binomcdf(19,12/19,7) = 0.9822
Cheers,
Stan H.
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