Question

I have a red, green and blue ball.
They can be repeated
I have 4 bags to put the balls into.
I have to use all 3 colors.
so I could have red red green blue or I could have red red blue green...etc, etc.
Is there a way to figure out how many possible combinations there are? The answer is supposed to be 36... I think. Any help would be appreciated.
I was able to do it with just 2 colors (red and green), but the 3 colors is stumping me. Thanks

Answer 1

Call the balls r,g,b,x
There are 4P3 = 12 ways to put 3 balls into the bags
There are 3 choices for the x ball

Answer 2

Thanks so much it makes sense.