SOLUTION: You guess on all of the answers on a 10 question quiz. If there are 4 possible answers for each question, what is the probability that you get 3 questions right?

Question 1033923: You guess on all of the answers on a 10 question quiz. If there are 4 possible answers for each question, what is the probability that you get 3 questions right?
Answer by rothauserc(4718) (Show Source): You can put this solution on YOUR website!
We use the binomial probability formula for this problem
:
Probability(P) = 1/4 for guessing a question correctly
:
P(guessing 3 problems correctly) = 10C3 * (1/4)^3 * (3/4)^7
:
Note 10C3 = 10! / (3! * 7!) = 10*9*8 / (3 * 2) = 120
:
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P(guessing 3 problems correctly) = 120 * (1/64) * (2187/16384) = .1%
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