The Gateway to Computer Science Excellence
+1 vote

The number of ways to choose n things from 2n things of which n are alike and rest are unlike?

in Combinatory by Active (3.2k points)
retagged by | 310 views
A is the answer???
Yes @Rahul. Could you please explain the methodology to solve?

1 Answer

0 votes
Best answer

We will have to take all cases in which we select one "indistinguishable" item, 2 "indistinguishable" item and so on till n "instinguishabe item. 

Let indistinguishable item be k-set items, distinct items be s-set items.( or vice versa it will not change answer)

When we select 0 item from set of k-items then we can have n from s-items, when 1 item from set of k-items then n-1 from s-set and so on......

So total ways is,

nC​​​​​​​​​​​​nC​​​​​​​​​​​.............+nC= 2(binomial)

by Boss (11.1k points)
selected by

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
50,737 questions
57,292 answers
104,909 users