Tiger Bait 7
Years ago, I posted a series of original logic challenges on PuzzleMonster.com inspired by those found in Raymond Smullyan’s classic logic puzzle book The Lady or the Tiger?. The challenge was to solve the puzzle and find the gold. Recently, I’ve brought them back with some new twists and been posting them on Reddit. It finally occurred to me, why not post them here, too? Hope you enjoy!
You are faced with 4 doors in a row. One of them leads to gold. Two of them lead to tigers. The remaining door leads either to a tiger or an orc.
The statement on the door leading to gold is true. The statement on any door leading to a tiger is false. The statement on any odd-numbered door leading to an orc is true. The statement on any even-numbered door leading to an orc is false.
Door 1. The door leading to gold is adjacent to a door leading to an orc.
Door 2. Either door 3 or door 4 leads to an orc.
Door 3. Either door 1 or door 2, or both, leads to a tiger.
Door 4. The door leading to gold is not adjacent to a door leading to an orc.
Which door leads to the gold?
Check out the discussion on Reddit or scroll down for the answer.
Suppose the statement on door 4 is true. Then it can’t lead to a tiger or an orc, so it must lead to gold. Since it’s true, it’s not adjacent to a door leading to an orc, so door 3 must lead to a tiger. Then the statement on door 3 is false, so neither door 1 nor door 2 lead to a tiger, but one of them must do so since there is a tiger remaining. This is a contradiction, therefore the statement on door 4 is false and the door leading to gold is in fact adjacent to a door leading to an orc.
This is what the statement on door 1 says, so door 1 is true and leads either to the gold or an orc. Suppose it leads to an orc. Then door 2 must lead to gold since it’s adjacent to door 1; but door 2 says that the orc is behind door 3 or 4. This is a false statement, which is impossible. Therefore, door 1 must lead to the gold. Door 2 leads to an orc, and tigers are behind doors 3 and 4.