Question 509381: A)a die is rolled 9 times and the number of times that two shows on the upper face is counted.if this experiment is repeated many times, find the mean for number of twos?
B)on a multiple choice test with 21 questions, each ? has four possible answers, one of them is correct.for students who guess at all answers, find the standard deviation for the number of correct answers?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A)A die is rolled 9 times and the number of times that two shows on the upper face is counted.
If this experiment is repeated many times, find the mean for number of twos?
mean = (number of trials)*(probability of getting a 2)
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B)on a multiple choice test with 21 questions, each ? has four possible answers, one of them is correct.for students who guess at all answers, find the standard deviation for the number of correct answers?
std = sqrt(npq) = sqrt(21*(1/4)(3/4) = 1.9843
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Cheers,
Stan H.
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