SOLUTION: A Multiple-choice test has 15 questions with each having 4 possible answers with one correct. Assume a student randomly guesses the answer to every question. a. What is the pro

Question 329409: A Multiple-choice test has 15 questions with each having 4 possible answers with one correct. Assume a student randomly guesses the answer to every question.
a. What is the probability of getting exactly 5 correct answers?

b. What is the probability of getting less than 6 correct answers?
I have to have this in by TODAY - August 6th, 2010. Please help!
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A Multiple-choice test has 15 questions with each having 4 possible answers with one correct. Assume a student randomly guesses the answer to every question.
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Binomial Problem with n=15 and p = 1/4
--------
a. What is the probability of getting exactly 5 correct answers?
P(x= 5) = 15C5*(1/4)^5*(3/4)^10 = binompdf(15,1/4,5) = 0.1651
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b. What is the probability of getting less than 6 correct answers?
P(less than 6) = binomcdf(15,1/4,5) = 0.8516
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Cheers,
Stan H.
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