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MathGroup Archive 2000

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Re: Combination Formula, HELP

  • To: mathgroup at smc.vnet.net
  • Subject: [mg21411] Re: Combination Formula, HELP
  • From: "Seok Gyun Kim" <sys3d at channeli.net>
  • Date: Thu, 6 Jan 2000 01:46:29 -0500 (EST)
  • Organization: 3D System
  • References: <84s6uf$q6e@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

4C2  means, for example, a combination of taking 2 different species
(without any order or discrimination by location when taken...See Note if it
is ordered.) out of 4 different species.
4C3  means taking 3 out of 4 . (This is exactly the same as leaving one out
of 4, that is 4C1, which has only 4 cases.)
So 4C3=4C1=4.

Likewise 4C4 =1, which means taking 4 out of 4, and only one possibility,
i.e. taking them all.
---------------------------
Note.
You have two boxes (lets call the boxes X and Y respectively, but they have
to be discriminated by order or any other reason) and put them cards
selected out of cards A,B,C,and D.
In the first box you have 4 degree-of-freedom, but in the latter 3. In this
situation the boxes are "ordered" (that is to be identified in the order,
location or any other reason).  In this "ordered" situation it has total
4*3=12 cases of possibilities: Permutation 4P2=4!/2!=12, not Combination.

~SGK/000105




::necro:: <necro at earendil.fsnet.co.uk__ (SPAM)>ÀÌ(°¡) ¾Æ·¡ ¸Þ½ÃÁö¸¦
news:84s6uf$q6e at smc.vnet.net¿¡ °Ô½ÃÇÏ¿´½À´Ï´Ù.
: hi, I don't suppose anyone could help me? I have a bit of a problem with
: some maths revision, I am stuck, the question is as follows:
:
: e.g.1 has 2 * 2, and in e.g.2 the numbers are 1 * 3, then the 3 is
doubled!
: why? Is it because it is partnered with a 1 and must have a higher value?
:
: e.g.1
: 4
:   C  =        4!                 4!                 24
:     2     ------------- = ------------- = --------------- = 6
:              (4-2)!2!        2! * 2!           2 * 2
:
:
: e.g.2
:
: 4
:   C  =        4!                 4!                 24
:     3     ------------- = ------------- = --------------- = 4
:              (4-3)!3!        1! * 3!           1 * 6
:
:
: thanks very much
:
: ::necro::
:
: --a circle of chalk, a ring of stones
:  and a house of arches to call the
:           far Gods home--
:
:
:




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