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2day’s IQ Test: The Switches and Light Bulbs

May 12th, 2008        

An IQ test here for you all – John is in a big mansion and he needs to match out the three switches located on the top floor for the three light bulbs located at the ground floor (not visible from top floor) but he can only get down once to check out the bulbs. No other devices were used, only hands.

More details:
There are 3 switches on the top floor – switch A, switch B and switch C and they were used to switch on the 3 light bulbs located at the ground floor. John needs to find out the switch for each of the bulbs but he can only get to the ground floor once to check the bulbs.

- Nothing tricky.
- Nothing to do with the wiring.
- John is alone in the mansion.
- No other devices were used for the checking.
- The switches are normal type which can only be on/off.

The question is ~ How John managed to know which switch goes to which light bulb by getting down once only. It is a test from a friend. Do you guys know the answer? Comment please.

Update: Wow! That’s cool! Someone has already got the answer in the comments, let’s make it more fun, so post your answer before checking out the comments.

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  1. May 12th, 2008 at 14:48 | #1

    Swith on A after 10 minutes swith on B and then go to the ground floor to check the bulb. Touch the light bulb that light on, the hotest bulb is switch A, other is switch B, the bulb witch light off is switch C.

  2. May 12th, 2008 at 15:12 | #2

    Simple…
    There is switch A B and C. Light bulb 1 2 and 3. First he switches each one to see which one is brighter. – The brighter is light bulb no 3 (let’s say with switch B).
    Then there are A and C – he switches one on and sees which one is which.

  3. May 12th, 2008 at 15:31 | #3

    the lighting is not visible from the top floor,
    DMZ got the right answer. How long it takes for you to figure that out? I gave up for this test actually hahaha

  4. May 12th, 2008 at 15:41 | #4

    john can switch on all de bulbs while scaling down de stairs he can make marks on de wiring, once he reach de landing he will folow whc wires that goes to wch bulbs. or easy…..he jus call out someone to be in de other floor. n check out wch bulb is lighting up wen he flick.TADAAAAA!!

  5. May 12th, 2008 at 15:47 | #5

    John is alone in the mansion.

  6. May 12th, 2008 at 19:35 | #6

    @webmaster: it just pops out in my mind, any price for the right answer? ehehehe..

  7. May 13th, 2008 at 08:29 | #7

    no prize for you DmZ, it’s an IQ test, hahahaha.

  8. isura
    May 13th, 2008 at 11:00 | #8

    bad engineering.. who would put the switches for the bulbs on one floor and the bulbs themselves on another?

  9. May 13th, 2008 at 16:27 | #9

    hahaha, it’s just an IQ test buddy

  10. isura
    May 13th, 2008 at 19:19 | #10

    to webmaster: sorry.. just kidding though

  11. winterlove
    May 15th, 2008 at 06:24 | #11

    so..what’s the answer? and who is the right one?

  12. May 15th, 2008 at 08:05 | #12

    the first comment is the answer, by dmz. Switch on one bulb (A) for 5 minutes , after that off it, then quickly switch on one more bulb (B) and left one off (C). So when you get to the ground floor, touch it, the hottest one should be (A) cuz it has been switched on for 5 minutes then off, and secondly the one that is switched on should be (B) and the one which is off will be (C). Cool right. lol.

  13. Pinky and the Brain
    May 18th, 2008 at 00:27 | #13

    Here is the real answer and you don’t have to wait 5 or 10 minutes. First turn on 2 two light switch on for 20 seconds. Then you turn one light switch off, leaving the other switch on. After that you go down to the lights. The light that is on is the switch that is on, the light that is warm by the touch is the light you just turned off, and the light that is cool is the switch which you didn’t turn on.

  14. Danielle Morrison
    May 19th, 2008 at 15:57 | #14

    The light bulbs are three different colour, and when he turns each one on in the dark mansion, the mansion will light up a different colour… he leaves the lights on then goes down stairs, remembering what colour the mansion glows for each switch! he then knows the answer! lol i hope im right

  15. May 20th, 2008 at 08:14 | #15

    To Pinky and the Brain: that another similar answer, great!

    To Danielle Morrison: erm, that is not right, because he can only get down once.

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