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An urn contains 9 blue, 7 white and 4 black balls. If 2 balls are drawn at random, then what is the probability that only one ball is white?
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An urn contains 9 blue, 7 white and 4 black balls. If 2 balls are drawn at random, then what is the probability that only one ball is white?
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Question 824306: Cud you help me solve this question
An urn contains 9 blue, 7 white and 4 black balls. If 2 balls are drawn at random, then what is the probability that only one ball is white?
Many thanks... Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! Cud you help me solve this question
An urn contains 9 blue, 7 white and 4 black balls. If 2 balls are drawn at random, then what is the probability that only one ball is white?
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One Method::
# of ways to succeed: 7*13 = 91
# of random pairs: 20C2 = 190
P(one white) = 91/190
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A Second Method::
P(2 white) = 7C2/20C2 = 21/190
P(2non-white) = 13C2/20C2 = 78/190
P(one white) = 1 - [(21+78)/20C2] = 1 - 99/190 = 91/190
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Cheers,
Stan H.
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