On a sunny weekend, two friends decide to visit a flea market together. At the booth of an elderly lady, they discover an interesting box. Inside they find three bags of small gold coins and a little note that says, "If you guess the right bag, you will receive a gold treasure." There is also a clue on each of the bags:
Bag 1: The gold treasure is not in bag 3.
Bag 2: The gold treasure is not in this bag.
Bag 3: The gold treasure is in this bag.
The two friends immediately set to work solving the puzzle. Which bag is the gold treasure in if only one of the clues is correct?
There is no clue to bag 1, so it can't be this one. The statements about bag 3 contradict each other. So one statement is correct and one is wrong. Since there is only one correct clue, the clue to bag 2 must be wrong. Therefore, the two friends choose the second bag and receive the gold treasure.