There are 10 barrels containing gold coins. In that, 9 barrels contains 1 gram gold coins and the other barrel contains 2 gram coins. Every coin looks to be same without any difference. As the barrels weigh more, so it cannot be lifted or moved from its place. There is a weighing machine which is allowed to weigh only once.
How to find that which of the barrels contain 2 gram coins.

• Totally there are 10 barrels. Take 1 coin from first barrel, 2 coins from second barrel, 3 coins from third barrel, as on for ten barrels. Now consider that if every barrel contains 1 gram coins, the total weight of the coins picked from the barrels will be 55 grams.
  If the 2 gram coin is in the first barrel, then the total weight will be 56 grams. If it is in second barrel, the total weight will be 57 grams.
  Just subtract the considered weight 55 from the total weight, you will get the barrel which contains 2 gram gold coins.
• 12 years agoHelpfull: Yes(4) No(0)
• There are 10 barrels in total.
  
  Just we Take 1 coin from first, 2 coins from second, 3 coins from third barrel and so on up to 10barrels.
  
  By consider that if every barrel contains 1 gram coins, the total weight of the coins picked from the barrels will be 55 grams.
  
  So,
  If the 2 gram coin is in the first barrel, then the total weight will be 56grams, because we take only 1gm coin from 1st barrel. So, 1gm increase in total weight.
  
  If it is in second barrel, the total weight will be 57 grams.
  
  Like that, Just subtract the considered weight 55 from the total weight, we will get the barrel which contains 2 gram gold coins.
• 12 years agoHelpfull: Yes(1) No(0)