Spot the Magnetized Coin among 39 Coins in 4 weighings !

[Commander]

One of the 39 identical coins was magnetized so that it weighs ( Y or Z ) heavier on one face and lighter on the other face when placed on a certain weighing scale. But it weighs X like the other normal coins when it is standing balanced on its side or edge.

Using the weighing scale just 4 times [means 4 weighings / judgments only].find that odd coin and determine its heavy or light face.

 

Please note only a digital weighing scale is to be used and each of the 38 normal coins weigh identically 1 Gram [X] while the magnetized coin weighs Y Grams [ Y > 1 Gram ] on one face and Z Grams [ Z < 1 Gram ] if face.down.

Edited August 11, 2015 by Commander