Find The Gold



Six bags of gold coins, each bag with a large unknown number of coins 
in it. However, only one of the bags has genuine gold coins in it and 
the others have fake coins in them. It is known that each coin of false 
gold weighs 100 grams and that each real coin weighs 110 grams apiece. 
The Teaser is, how, using only a simple bathroom type scale and with
only ONE weighing, can the genuine gold be deduced? 
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Answer:
Mark each bag with a number, from one to six. Take one coin from bag 
number one, two coins from bag number two, three from number three and 
so on. You will now have 1+2+3+4+5+6 coins...21coins in all, both real 
and fake coins mixed together. In a single weighing one would expect 
to see 2,100 grams IF all the coins were fake. The number of tens of 
grams over that amount signifies the bag number of the genuine coins. 
For example, bag number three containing real coins would show up as 
3 coins x 10 grams overweight, 2,140 grams....