a) We have three standard 6-sided dice, colored red, yellow, and green. In how many ways can we roll them to get a sum of 9? The dice are colored so that a red 2, yellow 3, and green 4 is a different roll from red 3, yellow 4, and green 2.
Notice
Roll Total Frequency
3 1
4 3
5 6
6 10
7 15
8 21
9 25
10 27 and the rolls of 11-18 will be in the same descending frequency order from 27 back to 1
So....there are 25 ways to roll a "9"
1 2 6 2 1 6 2 6 1 3 5 1 5 1 3
1 3 5 2 2 5 3 1 5 4 1 4 5 2 2
1 4 4 2 3 4 3 2 4 4 2 3 5 3 1
1 5 3 2 4 3 3 3 3 4 3 2 6 1 2
1 6 2 2 5 2 3 4 2 4 4 1 6 2 1
And notice that, no matter that the dice have different colors, that every possibility has been accounted for.
For instance.....for a roll of 2-3-4....we have 6 different possibilities as denoted in the table :
Red 2 Yellow 3 Grren 4
Red 2 Yellow 4 Green 3
Red 3 Yellow 2 Green 4
Red 3 Yellow 4 Green 3
Red 4 Yellow 2 Green 3
Red 4 Yellow 3 Green 2
So....there sre 25 distinguishable ways to roll a "9' with three different colored dice.