A lightbulb in a windowless room is connected to two switches outside, marked A and B. Switch A turns the light on, but only if Switch B is turned OFF. If Switch B is turned ON, the light stays off regardless of Switch A. Currently, the light is on. What are the positions of Switch A and Switch B?
Switch A is ON and Switch B is OFF.
The light can only illuminate when Switch A is ON and Switch B is OFF. Since the light is currently on, Switch A must be ON and Switch B must be OFF.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Easy. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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