# Thread: Combanition and premutation

1. ## Combanition and premutation

Hello, I am having a difficult time trying to figure out this problem. I can't seem to figure out if it is combination with no repetition or combination with repetition. Can anyone help me and please be descriptive.

In a storage facility for an automobile parts firm, four boxes are labeled for a particular part. If 36 of these parts are placed in the boxes at random, what is the probability that all parts are in the same box.

2. Originally Posted by enro
In a storage facility for an automobile parts firm, four boxes are labeled for a particular part. If 36 of these parts are placed in the boxes at random, what is the probability that all parts are in the same box.
The wording implies that we can treat the parts as identical and the boxes different,
We can put N identical objects into K distinct cells in $\dbinom{N+K-1}{N}$ ways.

If we want the number of ways in which no cell is empty then the answer is $\dbinom{N-1}{N-K}$.

For this question divide the second by the first and subtract that from 1.