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Atleast one blue marble

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by hariharakarthi » Mon Aug 03, 2009 9:06 am
A bag of 10 marbles contains 3 red marbles and 7 blue marbles. If two marbles are selected at random, what is the probability that at least one marble is blue?

Explain ans in detail.
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by gmat_dest » Mon Aug 03, 2009 9:08 am
Probability of at least one blue = 1 - Probability of all red

Probability of both red = 3/10 * 2/9 = 1/15

So, probability of at least one blue = 14/15.
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by maihuna » Mon Aug 03, 2009 9:11 am
No marble is blue means both are red: = 3/10*2/9 = 1/15

So at least one blue = 1-1/15 = 14/15
Charged up again to beat the beast :)
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