Question 98621: QUESTION: There are 8 red, 3 blue, and 12 black marbles in a bag. If 3 are selected, what is the probability that all are red or all are blue?
WHAT I HAVE:
8/23 * 7/22 * 6/21 + 3/23 * 2/22 *1/21 = 336/10626 + 6/10626 = 57/1771
Answer by Nate(3500)   (Show Source):
You can put this solution on YOUR website! There are 23 marbles in all ...
Chances of selecting a red ball: 8/23
Chances of selecting a red ball again: 7/22
Chances of selecting a red ball once more: 6/21
(8/23)(7/22)(6/21) = 336/10,626 = 168/5,313 = 56/1,771
There are 23 marbles in all ...
Chances of selecting a blue ball: 3/23
Chances of selecting a blue ball again: 2/22
Chances of selecting a blue ball once more: 1/21
(3/23)(2/22)(1/21) = 6/10,626 = 1/1,771
56/1,771 + 1/1,771 = 57/1,771
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