# The Twelve Coin Balance Problem Answer

#### Here is the full solution to the classic old puzzle! Click here to see the puzzle

 KEY TO DIAGRAMS: ? = a coin that may be too light or too heavy H = a coin that may be too heavy L = a coin that may be too light G = a coin that is definitely good

## The Solution:

#### ### WEIGHING 2:b ? ? ? G G G Weigh three of the untried coins against three good coins. There are three possible outcomes:

 Just out of interest... Here's an old silver three penny piece and also a six penny piece. (The six penny piece is about 2cm across which is roughly the size of a modern penny.) It's sad to think that even the old six pence is only worth 2½p. Heads Tails

#### ### WEIGHING 3:c Ld G We know either Ld is light or Hd is heavy. Weigh Ld against a good coin. There are two possible outcomes:

 Did you spot our fake? Here's a real old threepenny piece! Fake!

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This solution to the Twelve Coin Balance Problem is