in Combinatory retagged by
874 views
5 votes
5 votes

The number of ways that one can divide $10$ distinguishable objects in $3$ indistinguishable non-empty piles, is:
$$
\left\{\begin{array}{c}
10 \\
3
\end{array}\right\}=9330
$$
In how many different ways can one do this if the objects are also indistinguishable?

in Combinatory retagged by
874 views

1 comment

$ \large{\colorbox{yellow}{Detailed video solution of this question with direct time stamp}}$
All India Mock Test 3 - Solutions Part 1

1
1

2 Answers

4 votes
4 votes

I made a mistake in reading the questions actually piles should be non-empty but I missed that point but no problem, I realized my mistake.

now comes the solution part it is the IOIB template so we have to divide 10 similar  objects into 3 similar boxes,

so we can find it manually3

 

A B C
1 1 8
1 2 7
1 3 6
1 4 5
2 3 5
2 2 6
2 4 4
3 3 4

In the above table all A, B, and C are indistinguishable boxes, and the number in their respective columns is the number of objects(indistinguishable).

now in the IOIB template order doesn’t matter as 1 1 8 and 1 8 1 are the same things 

edited by

4 Comments

@MunchyMoo Then answer will be 14 these 8 ways in 3 piles and 5 ways in 2 piles and 1 way in 1 pile.

1
1

@Swarnava Bose There might be a formula I don't know about it, but it is the most efficient way to solve. Thank you for identifying the mistake

0
0

@svmkumar28 https://gateoverflow.in/421287/%23self-doubt here it is the explanation for 9330.

0
0
3 votes
3 votes
If both the objects and the piles are indistinguishable, a division is characterized solely by the number of objects in a pile.

We can easily list these different possibilities systematically:
$$
\begin{aligned}
8-1-1\\7-2-1\\6-3-1\\5-4-1\\4-4-2 \\ 6-2-2\\5-3-2\\4-3-3
\end{aligned}
$$
Recall that the piles should not be empty. So we can do this in eight ways.
edited by

1 comment

instead of doing this manually, is there any shortcut or formula ?
0
0
Answer:

Related questions

Quick search syntax
tags tag:apple
author user:martin
title title:apple
content content:apple
exclude -tag:apple
force match +apple
views views:100
score score:10
answers answers:2
is accepted isaccepted:true
is closed isclosed:true