Question 605207
This is more of a logic puzzle than a math problem.
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Throw Switch #1 to the "ON" position, and leave it in that position for a couple of minutes. Then set Switch #1 back to the "OFF" position and quickly throw Switch #2 to the "ON" position. Immediately go upstairs and observe the bulb.
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If the light is on, Switch #2 controls the light because it is the only switch in the "ON" position.
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If the light is off then Switch #2 does not control the bulb. That being the case, feel the bulb. If the bulb is very warm to the touch, Switch #1 turned it on previously, so it (Switch #1) controls the bulb.
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But if the light is off, and it is cool to the touch, then neither Switch #1 nor Switch #2 turned the light on, so the light must be controlled by Switch #3.
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