### Brain Teasers

# Where's the Gold?

Two boxes are labeled "A" and "B". The sign on box A says, "The sign on box B is true and the gold is in box A". The sign on box B says, "The sign on box A is false and the gold is in box A". Assuming there is gold in one of the boxes, which box contains the gold?

1) Box A

2) Box B

3) You can't determine from the information given.

1) Box A

2) Box B

3) You can't determine from the information given.

### Answer

3) You can't determine from the information given.The sign on box A says, "The sign on box B is true and the gold is in box A". The sign on box B says, "The sign on box A is false and the gold is in box A". The following argument can be made: If the statement on box A is true, then the statement on box B is true, since that is what the statement on box A says. However, the statement on box B states that the statement on box A is false, which contradicts the original assumption. Therefore, the statement on box A must be false. This implies that either the statement on box B is false or that the gold is in box B. If the statement on box B is false, then either the statement on box A is true (which it cannot be) or the gold is in box B. Either way, the gold is in box B.

However, there is a hidden assumption in this argument, namely, that each statement must be either true or false. This assumption leads to paradoxes; for example, consider the statement: "This statement is false." If it is true, it is false; if it is false, it is true. The only way out of the paradox is to deny that the statement is either true or false and label it meaningless instead. Both of the statements on the boxes are therefore meaningless and nothing can be concluded from them.

Hide Answer Show Answer

## What Next?

View a Similar Brain Teaser...

If you become a registered user you can vote on this brain teaser, keep track of which ones you have seen, and even make your own.

### Solve a Puzzle

Comments hidden to avoid spoilers.

## Follow Braingle!