Yahoo Answers: Answers and Comments for I need help with a probability question please!? [Mathematics]
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enMY
Thu, 17 Dec 2009 07:19:02 +0000
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Yahoo Answers: Answers and Comments for I need help with a probability question please!? [Mathematics]
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From fireFox: The number of ways Jim can pick six marbles ou...
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Thu, 17 Dec 2009 10:49:52 +0000
The number of ways Jim can pick six marbles out of 13 is 13C6 = 1716 ways.
Assuming that Jim picks the other five marbles that Sally did not pick, the sixth mable will be among those that Sally picked. The number of ways this (exactly one match) is possible is 5C5*8C1 = 8 ways.
Therefore there are 1716  8 = 1708 ways that Jim picks more than one marble, i.e., at least two marbles, that Sally picked, and the probability is 1708/1716 = 0.995 that Sally wins.

From MathMan TG: There are 13 C 6 different sets of marbles Jim...
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Thu, 17 Dec 2009 08:27:46 +0000
There are 13 C 6 different sets of marbles Jim can pick = 1716
In order for Jim to win, he has to pick all 5 marbles which Sally did *not* pick,
and then necessarily he'll pick one of hers.
There are only 8 ways for that to happen, corresponding to the 8 marbles Sally picked.
So Sally's chances are very good in this game: 1708 / 1716, about 99.5 %