wu :: forums
        (http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi)
      

        riddles >> medium >> Tough question
        
(Message started by: Polymath101 on Apr 26th, 2009, 8:07pm)
Title: Tough question
Post by Polymath101 on Apr 26th, 2009, 8:07pm
Suppose an octahedron consists of twelve rods all of equal length and forming eight equilateral triangles -- the eight sides of the octahedron. If any three of the rods are painted white and the rest black, how many distinct patterns are possible?
Title: Re: Tough question
Post by Grimbal on Apr 27th, 2009, 12:41am
Do you count mirroring as distinct patterns?  ::)
Title: Re: Tough question
Post by towr on Apr 27th, 2009, 7:25am
Let's see if I can get it right for once
[hide]7 if mirroring doesn't count as distinct, 11 if it does.[/hide]
Title: Re: Tough question
Post by Grimbal on Apr 28th, 2009, 9:56am
Hint:  It should be the same as for the cube.
Title: Re: Tough question
Post by towr on Apr 28th, 2009, 10:26am

on 04/28/09 at 09:56:47, Grimbal wrote:
Hint:  It should be the same as for the cube.
You mean the same as in the problem with the cube and four lights on the corners? Or the same as if we had a cube here?
Title: Re: Tough question
Post by Grimbal on Apr 28th, 2009, 10:22pm
In the sense of: paint 3 edges of a cube.
Title: Re: Tough question
Post by Grimbal on Apr 29th, 2009, 6:32am
Anyway, I find [hide]9 or 13 depending on whether mirror images are distinct[/hide]


Powered by YaBB 1 Gold - SP 1.4!
Forum software copyright © 2000-2004 Yet another Bulletin Board