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.
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