Six grocers sell an identical brand of coffee bean cans, in which each can is advertised as weighing exactly 4ounces. However, one of these grocers is dishonest; in that one of them sells a can that...

Six grocers sell an identical brand of coffee bean cans, in which each can is advertised as weighing exactly 4ounces. However, one of these grocers is dishonest; in that one of them sells a can that weighs only 3 ounces. If a scale can only be used once, what is the least amount of money that will be spent in order to determine which grocer is dishonest.