Question 870230: A student randomly guesses at 20 multiple choice questions. Each question has 4 possible answers with only one being correct, and each is independent of every other question.
find the probability that the student guesses 4 right, 3 correctly, more than 8 correctly, between 4 and 6 inclusively, would any of these be likely to occur?
Answer by ewatrrr(24785)   (Show Source):
You can put this solution on YOUR website! p(correct) = .25, n = 20
P(x = 4) = binompdf(20, .25, 4)= .1897
P(x = 3) = P(x = 3) = binompdf(20, .25, 3) = .1339
p(x > 8) = 1 - P(x = 7) = binomcdf(20, .25, 7) = .0409
P( 4≤ x ≤ 6) = .7858 - .7749 = .0111
P( x ≥ 4 ) = 1 - binomcdf(20, .25, 3)= .7748
P(x ≤ 6) = binomcdf(20, .25, 6)= .7858
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