SOLUTION: A book shelf containing 20 books of which 12 are on circuit theory and 8 are on Mathematics. If three books are taken out at random, find the probability that all the three are on

Question 245303: A book shelf containing 20 books of which 12 are on circuit theory and 8 are on Mathematics. If three books are taken out at random, find the probability that all the three are on the same subject.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A book shelf containing 20 books of which 12 are on circuit theory and 8 are on Mathematics. If three books are taken out at random, find the probability that all the three are on the same subject.
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# of ways to get 3 of the same kind: 12C3 + 8C3 = 220 + 56 = 276
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# of possible sets of 3: 20C3 = 1140
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Probability = 276/1140 = 0.242
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Cheers,
Stan H.
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