Here’s a question I got from my father:
In front of you are 6 bags, each one of them has 10 gold coins. 1 of these bags, however, is filled with coins with a slight impurity. The gold coins all weigh 1 ounce, while the impure coins weigh 1.01 ounces. You have a scale (a scale, not a balance, so this thing just tells you how much something weighs). You are allowed to make only 1 weight measurement. How can you determine which bag has the impure coins?