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Re: REALLY OT: News Flash

On 21 Feb 2007, Mike McCarty wrote:
> Chris Bannister wrote:
> >Or the 12 billiard balls where one is lighter/heavier and all you have
> >is a set of balance scales.
> >
> >You have to find which one it is plus whether its lighter or heavier in
> >3 weighings.
> >
> >I think/hope its 3 :-)
> I see how to do it in 4. In fact, I found two ways. I haven't
> found a way in 3 (yet).
> How about, you have N bags of coins. Each bag has some number
> of coins in it, each one has at least N coins. You know that
> one of the bags has counterfeit coins in it, and you know that
> the counterfeit coins each weigh one gram less than real coins.
> You have a scale. How, in one weighing, can you find which
> bag has the counterfeit coins?
> Mike

Hint: think about swapping some of the coins around.

Anthony Campbell - ac@acampbell.org.uk 
Microsoft-free zone - Using Linux Gnu-Debian
http://www.acampbell.org.uk (blog, book reviews, 
on-line books and sceptical articles)

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