engineering intelligence MCQ #954

You are in a room with 3 light switches. Each switch corresponds to one of three light bulbs in a room. Each light bulb is either on or off. You can't see the bulbs from where you are, but you can turn the switches on and off as many times as you want. How can you figure out which switch controls which light bulb?

engineering intelligence MCQ #954

  1. Question 1

    Q1. You are in a room with 3 light switches. Each switch corresponds to one of three light bulbs in a room. Each light bulb is either on or off. You can't see the bulbs from where you are, but you can turn the switches on and off as many times as you want. How can you figure out which switch controls which light bulb?

    • A) Turn two switches on for 5 minutes, then turn one off
    • B) Turn one switch on for 5 minutes, then turn it off and turn another on
    • C) Turn one switch on and wait
    • D) None of the above

    Answer: Turn two switches on for 5 minutes, then turn one off

    Explanation: Turn two switches on for 5 minutes. Then, turn one off. Go into the room. The bulb that is on corresponds to one of the switches that was left on. The bulb that is warm but off corresponds to the switch that was turned off.