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

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CEO
Joined: 21 Jan 2007
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There are 5 red marbles, 3 blue marbles, and 2 green [#permalink]

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25 Feb 2008, 09:00
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

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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You tried your best and you failed miserably. The lesson is 'never try'. -Homer Simpson

Kudos [?]: 1022 [0], given: 4

SVP
Joined: 29 Aug 2007
Posts: 2473

Kudos [?]: 832 [0], given: 19

Re: marbles - different colors [#permalink]

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25 Feb 2008, 12:53
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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Kudos [?]: 832 [0], given: 19

CEO
Joined: 29 Mar 2007
Posts: 2554

Kudos [?]: 500 [0], given: 0

Re: marbles - different colors [#permalink]

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25 Feb 2008, 19:35
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

Kudos [?]: 500 [0], given: 0

Re: marbles - different colors   [#permalink] 25 Feb 2008, 19:35
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