The Bulb Man

  • Then that wouldn't be the same problem, and would require a different solution...

  • Looks like McCool got the answer to the Gerald + Donald = Robert question.  Here's how it works (Long Post):

    We know that D = 5 to start with, so we replace that letter in the equation:

      GERAL5

    + 5ONAL5

    --------

      ROBERT

    We know that 5 + 5 = 10, so we carry the 1 and we now know that T = 0. 

          1

      GERAL5

    + 5ONAL5

    --------

      ROBER0

    Next we look at E + O = O.  E cannot equal 0 since we already know that T = 0.  So E + O cannot be equal to O unless we carried a 1 over from the column to its right (R + N = B), and then E + 1 would have to equal 10.  So now we have:

       1  1

      GERAL5

    + 5ONAL5

    --------

      ROBER0

    E + 1 + O = O + 10 can be simplified to E + 1 = 10.  The answer is then E = 9.

      11  1

      G9RAL5

    + 5ONAL5

    --------

      ROB9R0

    Now we know that A + A = 2A, which is even by definition.  So for the A + A column to equal 9, there has to be a 1 carried over from the 1 + L + L column to its right.  This means that A + A + 1 = 9, giving us A = 4:

      11 11

      G9R4L5

    + 5ON4L5

    --------

      ROB9R0

    We also know that L + L = 2L.  2L + 1 is an odd number by definition, so R (1 + L + L) must be odd.  Since R is odd, and 1 + G + 5 = R, G must also be an odd number.  Since there is no 1 carried over from G + 5 + 1, G + 5 + 1 is less than 10.  Therefore, G < 4.  G is in the set {1, 3}.

    If we substitute possibility for G in 1 + G + 5, we get 1 + 3 + 5 = 9 or 1 + 1 + 5 = 7 for R.  Since E = 9, G must equal 1 and R = 7.

      11 11

      1974L5

    + 5ON4L5

    --------

      7OB970

    Since we carried a 1 from 1 + L + L earlier, we know that 1 + L + L = 17.  Therefore L = 8.

      11 11

      197485

    + 5ON485

    --------

      7OB970

    We also know that N + 7 >= 10, since we carried a 1.  This means that N >= 3.  Since B = 7 + N, and we've narrowed B down to {3, 6}, we'll plug them in.  If B = 3 then N = 6.  If B = 6 then N = 9.  Since E = 9, N must be 6, and B is 3.

      11 11

      197485

    + 5O6485

    --------

      7O3970

    By process of elimination, O is 2.

      11 11

      197485

    + 526485

    --------

      723970

    So GERALD + DONALD = ROBERT is 197485 + 526485 = 723970.

  • I've almost got a solution going where the initial clue you gave (D=5) is not needed.

    I start off with the e + o = o column.  e has to be 9 in this situation with the carry-over from the previous column.  Since a + a = 9, a has to equal 4 and the column recieves a carry-over from the previous column.

  • well fine but

    "D'you know that my next door neighbor has three rabbits? "

  • For the trapped in a room question. Do I have a cell phone with me? Because if so then I want to call Jack Bauer to come get me out. Plus then I will be famous since they can have a full 24 hours dedicated to this problem.

  • LOL.  As long as you have a cell phone, how about just give yourself a high-powered laser beam, or a couple of paperclips, bubblegum and a toilet paper roll you can use to get our McGyver style?

  • The only problem is that E could be 0 in that case, since you haven't defined D = 5 and therefore T = 0 yet.  So you don't know if there's a carry to the next position over from E + O = O or not...  It'd be interesting to see if there were another solution where E = 0, but I kinda doubt it

  • The heat dissapation of the bulbs might throw off Amit's or my solution:

    A variant on Amit's answer:

    Turn on switch one and wait a minute then turn it off.

    Turn on switch 2, wait two minutes and turn it off.

    Turn on switch 3

    The bulb that is OFF and WARM is switch 1

    The bulb that is OFF and HOT is switch 2

    The bulb that is ON is switch 3

    The bulb that is COLD is switch 4.

    If the bulb's get hot immediately, then "ON and NOT HOT" will never be a state. If they cool instantly then "OFF and WARM" or "OFF and HOT" and perhaps "COLD" will either not be a state or will be indistinguishable.

    The short version is that you have to devise a way of the bulbs maintaining at least a two bit state (ON/OFF, HOT/COLD).

  • This might gauge your thought processes but I've always perferred something more specific to the job being performed. When I was interviewing for DBA's for a group I was running, one of the questions I asked was:

    You arrive at work at 8:36AM. Upon arrival you are informed by the Accounting Staff that the database crashed at 6:37PM the previous night. They are now asking that you restore the database to 4:36PM the previous night. Describe what you would need to do?

    You'd be surprised the number of candidates that started talking about backups and trans log and restoring to a "point-in-time." Which was half the question. A lot smaller number answered the second half of the question...

    Certainly sorted the chaff from the wheat. 

  • Turn on 3 of the switches for different lengths of time.

    Go into each room and feel the bulbs.

    The globe that hasn't been switched on will be cold.

    The globe that was on the longest will be the hottest.

     

    A man is found dead in the middle of a paddock with a back pack on. He was not murdered. He did not commit suicide. How did he die?

     

     

     

    Jame.

     

  • So Mike C not a 24 fan? Jack Bauer is the newer tougher MacGyver. Heck MacGyver would never shoot a gun.

  • LOL.  Yeah but McGyver once made a bomb out of swamp gas he captured with a piece of bamboo...  That's a tough act to follow   Hehe - he never actually needed a gun, just some paperclips, toilet paper, 6 blades of grass and a flexible drinking straw to create a small-scale WMD

  • Heart attack?

  • i would shoot myself and come back as a ghost..

    that way i would move freely from room to room without opening or closing any of the doors

  • I also note it does not clearly state that bulbs are functional or not, or even if the wiring is done correctly.

    One could just keep flashlights next to each door and then it would not matter.

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