SOLUTION: what is the probability of getting 2 answers correct on an 8 question 5 choice multiple choice exam.

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Question 1083140: what is the probability of getting 2 answers correct on an 8 question 5 choice multiple choice exam.

Found 3 solutions by Boreal, natolino_2017, Alan3354:
Answer by Boreal(15235)   (Show Source):
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8C2 number of ways (which is 28)(1/5)^2(4/5)^6, which are the probabilities of getting it right or wrong.
8C2=8!/2!6!=8*7/2=28
probability is 0.2936, if random guessing occurs.
Expected value is 8*1/5=1.6, so 2 is a likely result for random guessing.

Answer by natolino_2017(77)   (Show Source):
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every answer is independt from the other.
First let's find the probability of getting one question right
P(answer one right) = 1/5.
So P(answer one wrong ) = 1 - 1/5 = 4/5
(P answer two right and six wrong) = 8C2 *(1/5)^2 (4/5)^6 = 114,688/390,625=
= 29.360%
@natolino_

Answer by Alan3354(69443)   (Show Source):
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Depends mostly on your knowledge of the material.