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It's a probability question. Let's say I had a box with 36 numbered b***s (9 red 9 blue 9 white 9 green) inside. And I had to pick 5 b***s from it. What are the odds that I'll get atleast 2 RED b***s?

Guest Mar 6, 2017
 #1
avatar+87309 
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I'm taking "odds" to mean "probability"

 

At least 2 red means :  2 red, 3 red,4 red or 5 red

 

There are C(36,5) possibilities

 

And for 2 red...we want to choose 2 of the 5 red and 3 of the other 31

Similarly...for 3 red, we want to choose 3 of the 5 red and 2 of the other 31, etc.

 

So we have

 

[ C(5,2)*C(31,3) + C(5,3)*C(31,2) + C(5,4)*C(31,1) + C(5,5)] / C(36,5)  =

 

1777 / 13464  ≈  13.2%

 

P.S. - the odds for this are 1777 to [13464 - 1777]   =  1777 to 11687

 

 

cool cool cool

CPhill  Mar 6, 2017

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