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# There are 5 red marbles, 3 blue marbles, and 2 green

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There are 5 red marbles, 3 blue marbles, and 2 green [#permalink]  25 Feb 2008, 08:00
There are 5 red marbles, 3 blue marbles, and 2 green marbles. If a user chooses two marbles, what is the probability that the two marbles will be a different color?
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Re: marbles - different colors [#permalink]  25 Feb 2008, 11:53
bmwhype2 wrote:
There are 5 red marbles, 3 blue marbles, and 2 green marbles. If a user chooses two marbles, what is the probability that the two marbles will be a different color?

= [10c2 - (5c2 + 3c2 +2c2)]/[10c2]
= [45 - (10 + 3 + 1)]/45
= 31/45
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Re: marbles - different colors [#permalink]  25 Feb 2008, 18:35
bmwhype2 wrote:
There are 5 red marbles, 3 blue marbles, and 2 green marbles. If a user chooses two marbles, what is the probability that the two marbles will be a different color?

2(5/10*3/9) + 2(5/10*2/9) + 2(2/10*3/9) --> 1/3+2/9+2/15 ---> 31/45
Re: marbles - different colors   [#permalink] 25 Feb 2008, 18:35
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# There are 5 red marbles, 3 blue marbles, and 2 green

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