Re: Re: Combinatorica questions!!!

• To: mathgroup at smc.vnet.net
• Subject: [mg20616] Re: [mg20606] Re: [mg20499] Combinatorica questions!!!
• From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
• Date: Thu, 4 Nov 1999 02:13:31 -0500
• Sender: owner-wri-mathgroup at wolfram.com

```It does seem rather trivial when you look at it the right way. It would have
been easier to see if the problem referred the the king, not a rook :)
--

> From: Rob Pratt <rpratt at email.unc.edu>
To: mathgroup at smc.vnet.net
> Date: Tue, 2 Nov 1999 02:35:36 -0500
> To: mathgroup at smc.vnet.net
> Subject: [mg20616] [mg20606] Re: [mg20499] Combinatorica questions!!!
>
> An approach to problem 1 that is simpler than those already given is to
> recognize that each path consists of a sequence of 14 moves, 7 of them to
> the RIGHT one space and 7 of them UP one space.  Hence a path is uniquely
> determined by specifying which 7 of the 14 moves are RIGHT (the rest are
> UP).  We are choosing 7 objects from among 14 positions, so the answer is
>
> Binomial[14,7]=3432
>
> Rob Pratt
> Department of Operations Research
> The University of North Carolina at Chapel Hill
>
> rpratt at email.unc.edu
>
> http://www.unc.edu/~rpratt/
>
> On Wed, 27 Oct 1999, Keren Edwards wrote:
>
>> Hi all!!
>>
>> 2 different questions:
>>
>> 1.    how many ways does a castle have to reach from the bottom left side
>> corner
>> of a chess board to the upper right corner of the board if he can
>> move right
>> and up only?
>>
>>
>>
>> 2.     you have 8 red identical balls, 9 purple identical balls and 7 white
>> identical ones.
>> a.  How many ways can you choose 10 balls with no matter to the
>> order of the balls?
>> b.  How many ways can you choose 10 balls with no matter to the
>> order of the balls, if each color must
>> be chosen once at least?
>>
>>
>>
>> Many thanx.
>>
>>
>>
>>
>
>
>

```

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