You are presented with ten burlap bags full of coins. Nine of these bags contain counterfeit coins; one bag contains real gold coins. A counterfeit coin is visually identical to a real coin, and you do not know which bag contains the real gold.
Each counterfeit coin weighs exactly 1 gram, while each real gold coin weighs 1.1 grams. You are given a digital scale, the type you’d see in a delicatessen, which accurately measures weight the nearest hundredth of a gram.
If you can identify which bag has the gold, you can keep it. You are allowed one and only one measurement on the scale, so choose wisely. You are permitted to open the bags.