Puzzle #1: 10 Bags of Coins
You have 10 bags; each bag contains 10 coins. In nine of the bags, every coin weighs exactly 1 gram. However, one of the bags holds counterfeit coins, which weigh 1.1 grams apiece. You don’t know which bag contains the false coins, and the weight difference is too subtle to feel with your hands. Luckily, you have a scale to help. It displays a precise and accurate numeric readout (for example, if you placed a raisin on the scale, it might display: “.58 grams”). Not so luckily, the scale’s battery is dying and after one use it will conk out.
How can you identify the bag with the heavier coins using only a single weighing on the scale? You are allowed to take coins out of their bags, but you only get to read one number from the scale.
Find the solution at the bottom of this page.
