There are several of this type of puzzle that have been around for years, but we think this pair of linked puzzles are amongst the best.
Both concern three different coloured boxes, which are red, white and blue, where one of the boxes contains a prize. Each of the boxes is labelled with a statement and from these statements you must deduce which box contains the prize.
In the first puzzle the boxes are labelled thus:
- Red Box - The prize is not in the Blue Box.
- White Box - The prize is not in this Box.
- Blue Box - The prize is in this Box.
Of these three statements, no more than one is true. So, where is the prize?
If the prize was in the Blue Box, the statements on the White and Blue Boxes would both be true. Similarly, if the prize was in the Red Box, the statements on the Red and White Boxes would both be true. In both cases, two true statements.
If the prize was in the White Box, only the statement on the Red Box is true, so the prize is in the White Box.
In the second puzzle the boxes are labelled thus:
- Red Box - The prize is not in the White Box.
- White Box - The prize is not in this Box.
- Blue Box - The prize is in this Box.
Of these three statements, one or more is true and one or more is false. So, where is the prize?
If the prize was in the Blue Box, all the statements on the Boxes would be true. Similarly, if the prize was in the White Box, all the statements on Boxes would be false.
If the prize was in the Red Box, the statements on the Red and White Boxes would be true, and the statement on the Blue Box would be false, so the prize is in the Red Box.