Step two

	Good coins	Light group	Heavy group
		Suspicious coins

Rearrange the coins, namely:

(A) Interchange 3 coins from the light group with the good coins.

Group 1	Group 2	Group 3

(B) Interchange the fourth coin from the light group
with a coin from the heavy group.

Group 1	Group 2	Group 3

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Weigh group 2 against group 3.

If the groups are in equilibroum, then The false coin is one of 3 coins interchanged at step (A). The false coin is lighter then the good coins.	If the plates switch positions, then The false coin is one of the coins interchanged at step (B). It is not known if the false coin is heavier or lighter then the good coin.	If the plates are in the previous position, then the false coin is among the remaining three heavy coins The false coin is heavier then the good coins.
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