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 :)