You are outside a room with three switches, one of which controls a lamp inside. You can flip switches as you wish, but can only enter the room once. How do you determine which switch controls the lamp?
Category: Brain · Difficulty: hard
Hint: Think about other properties besides light, like heat.
Answer
turn on switch 1 for several minutes, then turn it off. turn on switch 2 and enter the room.
Explanation
Turn on switch 1 for several minutes, then turn it off. Turn on switch 2 and enter the room. If the lamp is on, switch 2 controls it. If the lamp is off but warm, switch 1 controls it. If the lamp is off and cool, switch 3 controls it.
This is a hard brain riddle — a tricky one that takes a little thought. The answer is turn on switch 1 for several minutes, then turn it off. turn on switch 2 and enter the room..
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