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A bag contains 3 red and 6 white tokens. Tokens are randomly selected and removed one at a time until the bag is empty. Find the probability that the red tokens are drawn consecutively.

 Mar 2, 2020
 #1
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This is analogous  to  the number of identitifable "words"  we can make from the letters  RRRWWWWWW  where  the "R's"  occur together

 

The "R's" can occur together in 7 ways :

1-2-3

2-3-4

3-4-5

4-5-6

5-6-7

6-7-8

7-8-9

 

And the  number of identifiable  draws  is           7!               

                                                                         ______  =     35

                                                                          3!  * 4! 

 

 

So....the  probability   is        7 / 35    =    1/5

 

 

 

cool cool cool

 Mar 2, 2020

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