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How many ways are there to put 6 boxes in 3 crates if the boxes are distinguishable but the crates are not?

 Apr 6, 2016
 #1
avatar+6251 
+4

How many ways are there to put 6 boxes in 3 crates if the boxes are distinguishable but the crates are not?

You can think of this as a 3 digit number in base 6.  Each digit represents how many boxes in that crate.

 

There are

 

\(6^3=216\) 

 

combinations, however they aren't all distinguishable.  As there are 3 crates any given distribution of the boxes into crates is indistinguishable within a group of 3! other distributions.  

 

For example 312 is indistinguishable from

123, 132, 213, 231, 321

 

So the final number is

 

\(\dfrac {216}{3!} = \dfrac{216}{6} = 36\)

 Apr 7, 2016
 #2
avatar+129845 
0

Here's my take on this one.......

 

Call the identifiable  boxes

A B C D E F

 

And I'm assuming that every crate  must contain at least one box.

 

We could select any 4 of the 6 boxes to put in one crate, then select 1 of the 2 remaining boxes to go into a second crate leaving the last box, by default, for the remaining crate....the number of ways to do this is :

4 1 1       6C4 * 2C1 * 1C1  = 30  ways

 

 

Or, we could select any 3 of the 6 boxes to put in one crate, then select 2 of the 3 remaining boxes to go into a second crate leaving the last box, by default, for the remaining crate....the number of ways to do this is :

3 2 1       6C3 * 3C2 *1C1  = 60 ways

 

Or, we could select any 2 of the 6 boxes to put in one crate, then select 2 of the 4 remaining boxes to go into a second crate leaving the last 2 boxes, by default, for the remaining crate....the number of ways to do this is :

2 2 2       6C2 * 4C2 * 2C2   = 90 ways

 

So....the total number of ways = 30 + 60 + 90  = 180 ways

 

 

 

 


cool cool cool

 Apr 7, 2016

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