Re: Combinatorica questions!!!

• To: mathgroup at smc.vnet.net
• Subject: [mg20606] Re: [mg20499] Combinatorica questions!!!
• From: Rob Pratt <rpratt at email.unc.edu>
• Date: Tue, 2 Nov 1999 02:35:36 -0500
• Sender: owner-wri-mathgroup at wolfram.com

```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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