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Friday, 9 December 2016

3 switch and light puzzle asked in interviews


3 switch puzzle 


 There are three switches outside the room . 


 Two Of which are useless , while one is connected to a lightbulb inside the room.

 You can on or off any switch any number of time (it also cover you can on or off any number of switch together) .

 You have one, and only one, opportunity to go inside the room and look . 

 Question is : How can you tell which switch goes to light?


2 comments:

  1. switch on the second switch for five minute and then switch it off and then immediately switch on 3rd one and enter the room. Touch the bulb:
    1> if buld is on then 3rd switch.
    2> if the buld is off but is hot then second switch.
    3> if the bulb is off and is cold first switch

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  2. I go out side 1switch on on 5 min and off the switch
    And on 2nd switch
    And gi in room
    When bulb is shine
    So 2 switch is connected to bulb
    When bulb is not shine but hot
    So 1 switch is connected to bulb
    When bulb not shine and not hot
    So 3 switch is connected to bulb

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