A windowless room contains 3 light bulbs, each connected to a switch outside the room. You can flip any of the switches in any order. You can then enter and look at the lights, but not touch the switches again. Which switch controls which light?
Flip on switches 1 & 2, wait a moment and switch off number 2. Enter the room. Whichever bulb is on is wired to switch 1, whichever is off and hot is wired to switch number 2, and the third is wired to switch 3.
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Answered by Emily F. • Oxbridge Preparation tutor
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