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 #1
avatar+129840 
+2

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.

 

 

 

cool cool cool

Aug 25, 2016
 #3
avatar+18 
0
Aug 25, 2016
 #2
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Aug 25, 2016

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