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The weighing twelve (12) balls riddle – which one is a different weight?

This is a riddle that a friend (Carl “Chunky” Benson) put to me a few years back. A few A4 pages of scribblings and I had accounted for an “answer” for almost all possible outcomes (almost), however, I never arrived at a complete solution.

There’s every chance that I’m just hopeless at Maths, so prove me wrong people ๐Ÿ™‚

Premise

  1. You have twelve (12) balls and a set of balance scales.
  2. One (1) of the balls is a different weight to the other eleven (11) balls.
  3. You are allowed to use the balance scales three (3) times.
  4. You need to determine which ball is the “odd one out” and whether it is heavier or lighter than the other balls.

Now these are balance scales I’m talking about. While a solution involving electronic scales would be effective, I don’t think it’s what the riddle’s architect had in mind ๐Ÿ˜‰

Balance Scales

Balance Scales

I’ve seen a few similar riddles such as this posted elsewhere on the Internet, however, several state that the ball is either heavier or lighter; a far easier problem to solve. Maybe it should be called something different than “weighing twelve…” as your solution mightn’t necessarily involve weighing all the balls.

Good luck!

Feel free to add any comments. If you require further clarification on any part of this riddle, please leave a comment, or you can email me at: ryan@kirgs.com

Ryan Kirgan lives in and works out of Sydney, Australia.

Ryan Kirgan

Ryan Kirgan

P.S – Any hate mail you want to write (after obsessing over this problem) can be sent to carl@mytrade.com.au ๐Ÿ™‚

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