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![[Post New]](/templates/default/images/icon_minipost_new.gif) 5 Feb 2008 23:42:14 IST
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guys i m very much confused in probability i dont know when to use permutation and when to use combination give me any example ??? what is d difference betn them???
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"If u win u need not have to explain and if u lose thn u should not be there to explain"
-Adolf Hitler |
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6 Feb 2008 00:05:32 IST
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the basic difference between the 2 is that
combination is the no of ways to simply choose certain items
permutations includes choosing as well as arranging the items
so if we select 4 objects from 8, it is 8C4
and if we select 4 and arrange it in a line
the answer is 8P4
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- Bill Gates |
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6 Feb 2008 00:27:52 IST
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there is only one difference between permutation and combination,and that is the language mentioned in the problem.....
for example,if the problem demands total no. of arrangements,then its better to opt for permutation,while only selecting requires use of combination.....
the trick is to identify whether the case requires arrangement or not.....
for ex,if u hav to find out total cases of taking only 4 people to a fair from a group of 5 persons a,b,c,d,e,it does not matter if the people u r takin are a,b,c,d or b,c,d,a or c,a,d,b.....as all these cases are identical as u r takin the same 4 persons....
but then if u r given 4 seats numbered 1 to 4 and asked to seat the 4 selected persons in any manner,then obviously u hav to consider the total no. of arrangements as a,b,c,d and b,c,a,d are different cases becoz in this problem,the ordering among the selected persons does matter as each seat has aparticular number....
in genera,all sums can be solved using the combination concept as nCm(m!)=nPm
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"Many of the things you can count,dont count....
Many of the things you cant count,really do count...."-Albert Einstein
"The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them"-William Bragg
"An inexplicable fact is infinitely preferable to an incomprehensible mystery"-F. Soddy
RISHIPRATIM MAZUMDAR
NIT DURGAPUR
1ST YEAR,ELECTRONICS AND COMMUNICATIONS
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7 Feb 2008 06:08:38 IST
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As locus says, The fundamental issue in permutations is the arrangement of things.. whereas
Combinations correspond to selection of things(and not their arrangement).We do not intend to arrange things,, we intend to select them.
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______________________________________________
Siddhant Shah
The trouble with doing something right the first time is that nobody appreciates how difficult it is.
You can't control the wind, but you can adjust your sails.
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