<PRE><B>Question 355507</B>
To solve grouping problems we use combination.

no. of ways to select r items from total n = nCr = n!/ [ r! * (n-r)!]


for example -

 no. of ways to select 2 people from 10 = 10C2 = 45


we use combination where problem is related to only grouping of items, 

arrangement is not considered.



for example- no. of ways to select 3 persons from total 5 names A,B, C, D and E

here ABC, CBA  and BAC  are same, these form only one group. 


If your concept have not been cleared, you are welcome for further help

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sudhanshu.cochin@gmail.com  , sudhanshu.cochin@yahoo.com 

 





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