Question
There are three switches outside a room and one controls a lamp inside. You may enter the room once. Which method identifies the switch?
Select an option. Your answer will be checked instantly.
Correct Answer: B. Use heat and light by turning one switch on, then off, and another on before entering.
Explanation:
One switch leaves the bulb warm, one leaves it lit, and one leaves it cold and dark.
These three states identify all three switches in one entry.
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