Question 108362
You are taking a multiple-choice quiz that consists of 3 questions. Each question has 4 possible answers, only one of which is correct.  To complete the quiz, you randomly guess the answer to each question.
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With 4 possible answers on each question,
P(correct) = 0.25
P(wrong) = 0.75
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  Find the probability of guessing 
(A) exactly 2 answers correctly, = binompdf(3,0.25,2)=0.1406...
(B) at least 2 answers correctly, = 1 - binomcdf(3,0.25,2)=0.0.15625... 
(C) less than 2 answers correctly.= binomcdf(3,0.25,1) = 0.84375
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Cheers,
Stan H.