Question 1041069: A multiple choice test consists of four questions. Each question has five possible answers of which only one is correct. A student guesses on every question. Find the probability distribution of X, the number of questions she answers correctly.
Table with x and P(X=x)
x= 1, 2, 3, 4 then
P(X=x)?
Found 2 solutions by stanbon, robertb:
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! multiple choice test consists of four questions. Each question has five possible answers of which only one is correct. A student guesses on every question. Find the probability distribution of X, the number of questions she answers correctly.
Table with x and P(X=x)
x= 1, 2, 3, 4 then
P(X=x)?
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Binomial Problem with p(correct) = 1/5 ; n = 4
P(X = 1 correct) = 4C1*(1/5)*(4/5)^3 = binompdf(4,1/5,1) = 0.4096
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P(X = 2 correct) = 4C2(1/5)^2*(4/5)^2 = binompdf(4,1/5,2) = 0.1536
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P(X = 3 correct) = binompdf(4,1/5,3) = 0.0256
etc.
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Cheers,
Stan H.
Answer by robertb(5830)  (Show Source):
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