I have 3 pieces of candy to place in 4 lunch boxes. In how many ways can I do this if:
(a) The candies are all different and the lunch boxes are all different?
Say the lunch boxes are red, blue and yellow and the candies are X,Y,Z
| Red | Blue | Green | ||
| XYZ | 0 | 0 | 1 | |
| 0 | XYZ | 0 | 1 | |
| 0 | 0 | XYZ | 1 | |
| XY | Z or 0 | Z or 0 | 2 | |
| XZ | 2 | |||
| YZ | 2 | |||
| XY | 2 | |||
| XZ | 2 | |||
| YZ | 2 | |||
| XZ, or YZ, or XY | 6 | |||
| X or Y or Z | 6 | |||
| TOTAL | 27 ways |
(b) The candies are all the same and the lunch boxes are all the same?
3 in 1 and none in the others
2 in one box and 1 in another
1 in each box
6 ways
(c) The candies are all the same and the lunch boxes are all different?
| Red | Blue | Green | ||
| 3 | 0 | 0 | 1 | |
| 0 | 3 | 0 | 1 | |
| 0 | 0 | 3 | 1 | |
| 2 | 1 or 0 | 1 or 0 | 2 | |
| 2 | 2 | |||
| 2 | 2 | |||
| 1 | 1 | 1 | 1 | |
| TOTAL | 10 ways |
(d) The candies are all different and the lunch boxes are all the same?
| box | box | Box | ||
| XYZ | 0 | 0 | 1 | |
| XY | Z | 0 | 1 | |
| XZ | Y | 0 | 1 | |
| YZ | X | 0 | 1 | |
| X | Y | Z | 1 | |
| TOTAL | 5 ways |
(e) Exactly two of the candies are the same (but the third is different) and all of the lunch boxes are different?
| Red | Blue | Green | ||
| XYY | 0 | 0 | 1 | |
| 0 | XYY | 0 | 1 | |
| 0 | 0 | XYY | 1 | |
| XY | Yor 0 | Y or 0 | 2 | |
| YY | X OR 0 | X OR 0 | 2 | |
| XY | 2 | |||
| YY | 2 | |||
| XY | 2 | |||
| YY | 2 | |||
| X | Y | Y | 1 | |
| Y | X | Y | 1 | |
| Y | Y | X | 1 | |
| TOTAL | 18 ways |
That is what I get :/ My answers should be checked though :)