SOLUTION: A student randomly guesses at 7 multiple choice questions. Each question has 5 possible choices. What is the probability that the student gets at most 1 correct answer?

Question 541911: A student randomly guesses at 7 multiple choice questions. Each question has 5 possible choices. What is the probability that the student gets at most 1 correct answer?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A student randomly guesses at 7 multiple choice questions. Each question has 5 possible choices. What is the probability that the student gets at most 1 correct answer?
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Binomial Problem with n = 7 and p(correct) = 1/5
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P(x = 0 or 1) = 7C0(1/5)^0*(4/5)^7 + 7C1(1/5)*(4/5)*6
= (4/5)^7 + 7*(1/5)*(4/5)^6
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= 0.5767
==============================
Cheers,
Stan H.
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