There are 100 coins divided into 10 stacks, with 10 coins in each stack. There are 90 genuine coins and 10 fake coins. A genuine coin weighs 2 ounces and a fake coin weighs 1 ounce. The 10 fake coins are contained in one of the stacks. You have a scale with which you can weigh any number of coins. Using only one weighing, describe how you would determine which stack contains the fake coins.
