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If three standard, six-faced dice are rolled, what is the probability 
that the sum of the three numbers rolled is 9? Express your answer as a common fraction.
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First of all, there are 6*6*6 = 6^3 = 216 possible different outcomes.
So, the entire space of events has 216 elements.
                    Of them
Triple  (6,2,1)  produces  3! = 6 different favorable triples with the sum of 9.
Triple  (5,3,1)  produces  3! = 6 different favorable triples.
Triple  (5,2,2)  produces       3 different favorable triples.
Triple  (4,4,1)  produces       3 different favorable triples.
Triple  (4,3,2)  produces  3! = 6 different favorable triples.
Triple  (3,3,3)  produces       1           favorable triple.
In all, there are  6+6+3+3+6+1 = 25 favorable triples.
The probability under the problem's question is  P =  = .    ANSWER
Solved.