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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 14 of 14. This is the beginning of the thread.
Posted by JohnX2 on May 9, 2002, at 19:11:41
Inside a room there are 4 lamps sitting on a table (A-D).Outside the room there are 4 levers (1-4).
Each lever can turn on or off one of the lamps (i.e.
when all 4 levers are on all 4 light bulbs will be on).There is a closed door to the room (seperating the levers
from the lamps).You can turn on the levers in any position you want (on/off),
and then open the door to observe the lamps (which ones
are on).Your goal is to figure out which lever control which lamp.
*Caveat*: You have only *2* trials to change the levers and then
observe the behavior of the lamps in the room.How do you solve the problem?
(If you've heard this before, hold the answer to your chest).
------------------------------------Inside room:
Lamp-A Lamp-B Lamp-C Lamp-D
--Door---------------------------------
outside room:
Lever-1 Lever-2 Lever-3 Lever-4
John
Posted by JohnX2 on May 9, 2002, at 19:18:54
In reply to A Quiz: Lightbulb switches, posted by JohnX2 on May 9, 2002, at 19:11:41
>
> Inside a room there are 4 lamps sitting on a table (A-D).
>
> Outside the room there are 4 levers (1-4).
>
> Each lever can turn on or off one of the lamps (i.e.
> when all 4 levers are on all 4 light bulbs will be on).
>
> There is a closed door to the room (seperating the levers
> from the lamps).
>
> You can turn on the levers in any position you want (on/off),
> and then open the door to observe the lamps (which ones
> are on).
>
> Your goal is to figure out which lever control which lamp.
>
> *Caveat*: You have only *2* trials to change the levers and then
> observe the behavior of the lamps in the room.
>
> How do you solve the problem?
>
> (If you've heard this before, hold the answer to your chest).
>
>
> ------------------------------------
>
> Inside room:
>
> Lamp-A Lamp-B Lamp-C Lamp-D
>
> --Door---------------------------------
>
> outside room:
>
> Lever-1 Lever-2 Lever-3 Lever-4
>
>
> JohnAlso, the lightbulbs are initially off (as well as
the corresponding levers).And, you can walk into the room.
John
Posted by Ron Hill on May 9, 2002, at 21:24:21
In reply to A Quiz: Lightbulb switches, posted by JohnX2 on May 9, 2002, at 19:11:41
John,
I enjoyed your quiz. I do not remember seeing it previously, but it seems fitting that a EE would present a logic test.
I figured out the answer, but first I want to know who to talk to about my prize. You? Lou? Dr Bob? Willow? Beardy? Do you want my physical address so you can mail my prize, or do you need my e-mail address to send me some e-bucks?
I'm not about to give out the answer until I know the status of my prize!
-- Ron
Posted by JohnX2 on May 9, 2002, at 21:55:19
In reply to Who's in charge of handing out the prizes? » JohnX2, posted by Ron Hill on May 9, 2002, at 21:24:21
> John,
>
> I enjoyed your quiz. I do not remember seeing it previously, but it seems fitting that a EE would present a logic test.
>
Oh, but the answer requires creative thinking...pure logic does not solve the problem.
> I figured out the answer, but first I want to know who to talk to about my prize. You? Lou? Dr Bob? Willow? Beardy? Do you want my physical address so you can mail my prize, or do you need my e-mail address to send me some e-bucks?
>
> I'm not about to give out the answer until I know the status of my prize!
>
> -- RonGreedy aren't we?
How about a pat on the back? Also, this is good inside info on a
off the wall question someone might ask you for a job interview... ;-)John
Posted by CtrlAlt n Del on May 9, 2002, at 22:01:57
In reply to Re: A Quiz: Lightbulb switches, posted by JohnX2 on May 9, 2002, at 19:18:54
Posted by Zo on May 10, 2002, at 2:00:52
In reply to A Quiz: Lightbulb switches, posted by JohnX2 on May 9, 2002, at 19:11:41
Posted by beardedlady on May 10, 2002, at 5:55:21
In reply to Re: Pass the ibuprofen. (nm) » JohnX2, posted by Zo on May 10, 2002, at 2:00:52
Posted by JohnX2 on May 10, 2002, at 13:35:57
In reply to A Quiz: Lightbulb switches, posted by JohnX2 on May 9, 2002, at 19:11:41
Posted by JohnX2 on May 10, 2002, at 13:38:31
In reply to hint: 98.6 (nm), posted by JohnX2 on May 10, 2002, at 13:35:57
U can mess with the levers all you want as long
as the door is closed. When you open the door
the levers must remain untouched.
Posted by JohnX2 on May 10, 2002, at 19:11:05
In reply to Who's in charge of handing out the prizes? » JohnX2, posted by Ron Hill on May 9, 2002, at 21:24:21
> John,
>
> I enjoyed your quiz. I do not remember seeing it previously, but it seems fitting that a EE would present a logic test.
>
> I figured out the answer, but first I want to know who to talk to about my prize. You? Lou? Dr Bob? Willow? Beardy? Do you want my physical address so you can mail my prize, or do you need my e-mail address to send me some e-bucks?
>
> I'm not about to give out the answer until I know the status of my prize!
>
> -- RonRon,
Do you want to go ahead and post your solution out of altruism.
Or are you still holding out for the $$$$s ? :-)John
Posted by Manda on May 11, 2002, at 6:57:07
In reply to Re: Who's in charge of handing out the prizes? » Ron Hill, posted by JohnX2 on May 10, 2002, at 19:11:05
Well... Here's my guess. Since you can fool with the levers when you're out of the room, you should turn one lever on for a little while, and then turn it off (w/out looking). Then turn on another lever, and go in the room. The light that is on (obviously) belongs to the second lever. By touching the lightbulbs of the other three, you can tell which belongs to the first lever. Repeat with the other 2 lamps/levers.
-Manda
Posted by JohnX2 on May 11, 2002, at 16:57:21
In reply to Manda's attempt at brilliance-- Ha!, posted by Manda on May 11, 2002, at 6:57:07
> Well... Here's my guess. Since you can fool with the levers when you're out of the room, you should turn one lever on for a little while, and then turn it off (w/out looking). Then turn on another lever, and go in the room. The light that is on (obviously) belongs to the second lever. By touching the lightbulbs of the other three, you can tell which belongs to the first lever. Repeat with the other 2 lamps/levers.
> -MandaManda is brilliant! You win. Ron copped out of giving
his solution, he wanted $$$.There is another possibility (this is the one
I came up with, but your's works just as well):1)flip on just lever 1 - note the lamp it controls
2)flip the 2nd and 3rd levers on,and then turn off
lever 3. Go in the room , the lamp on is for lever 2.
touch the two remaining lamps (they will be off, and
you already figured out lever 1 and 2). The hot bulb is lever
3, the cool bulb is lever 4.A little less hand burning :-)
Good Work!
John
Posted by Ron Hill on May 11, 2002, at 22:48:04
In reply to Re: Who's in charge of handing out the prizes? » Ron Hill, posted by JohnX2 on May 10, 2002, at 19:11:05
> Do you want to go ahead and post your solution out of altruism. Or are you still holding out for the $$$$s ?
-----------John,
Enclosed is my solution to the originally stated brain teaser (i.e. without the freedom to touch the light bulbs).
~~~~~~~~~~~~~~~~~~~~~~
STATEMENT OF PROBLEM:Inside a room there are 4 lamps sitting on a table (A-D).
Outside the room there are 4 levers (1-4).
Each lever can turn on or off one of the lamps (i.e.
when all 4 levers are on all 4 light bulbs will be on).There is a closed door to the room (seperating the levers
from the lamps).You can turn on the levers in any position you want (on/off),
and then open the door to observe the lamps (which ones
are on).Your goal is to figure out which lever control which lamp.
*Caveat*: You have only *2* trials to change the levers and then
observe the behavior of the lamps in the room.How do you solve the problem?
(If you've heard this before, hold the answer to your chest).
------------------------------------Inside room:
Lamp-A Lamp-B Lamp-C Lamp-D
--Door---------------------------------
outside room:
Lever-1 Lever-2 Lever-3 Lever-4
~~~~~~~~~
SOLUTION:1. Configure switches, on and off, as follows;
SW-1 on
SW-2 off
SW-3 on
SW-4 off2. Open the door and record the on/off status of each light bulb.
3. Close the door and reconfigure the switches, on and off, as follows;
SW-1 off
SW-2 off
SW-3 on
SW-4 on4. Open the door and record the on/off status of each light bulb.
5. From these collected data, one can calculate the particular one-to-one correspondence between switches and bulbs. In other words, which switch operates which bulb.
John, to demonstrate that the algorithm works, randomly select a connection correspondence between switches and bulbs {e.g. (1, B), (2, C), (3, A), (4, D)}, and then, using your selected (secret) correspondence, determine which bulbs are lit in Steps 2 and 4 as instructed above. Send me (post) this information and, in return, I will tell you which switch operates which bulb.
In other words, tell me which bulbs light when the switches are configured, firstly, as:
SW-1 on
SW-2 off
SW-3 on
SW-4 offAnd, secondly, as
SW-1 off
SW-2 off
SW-3 on
SW-4 onAnd, in return, I can tell you which switch operates which bulb.
-- Ron
Posted by JohnX2 on May 12, 2002, at 0:40:00
In reply to Re: My Solution to Lights and Switches » JohnX2, posted by Ron Hill on May 11, 2002, at 22:48:04
Yes you are brilliant Ron. And you don't burn your hand.My brain fart, I typed this up quickly and couldn't remember
the details off the top of my head. I should have had the restriction
that only 1 lever could be turned on at a time. I should have thought
a little more about the possibilities for solutions for my quiz
as stated! I personally didn't try to solve it the straightforward way,
I wonder if I would have figured it out...hmmm.I guess it makes it more fun...having 2 solutions.
You and Manda are co-champs. Sorry, skimping on e-bucks.
- John
> > Do you want to go ahead and post your solution out of altruism. Or are you still holding out for the $$$$s ?
> -----------
>
> John,
>
> Enclosed is my solution to the originally stated brain teaser (i.e. without the freedom to touch the light bulbs).
>
> ~~~~~~~~~~~~~~~~~~~~~~
> STATEMENT OF PROBLEM:
>
> Inside a room there are 4 lamps sitting on a table (A-D).
>
> Outside the room there are 4 levers (1-4).
>
> Each lever can turn on or off one of the lamps (i.e.
> when all 4 levers are on all 4 light bulbs will be on).
>
> There is a closed door to the room (seperating the levers
> from the lamps).
>
> You can turn on the levers in any position you want (on/off),
> and then open the door to observe the lamps (which ones
> are on).
>
> Your goal is to figure out which lever control which lamp.
>
> *Caveat*: You have only *2* trials to change the levers and then
> observe the behavior of the lamps in the room.
>
> How do you solve the problem?
>
> (If you've heard this before, hold the answer to your chest).
>
>
> ------------------------------------
>
> Inside room:
>
> Lamp-A Lamp-B Lamp-C Lamp-D
>
> --Door---------------------------------
>
> outside room:
>
> Lever-1 Lever-2 Lever-3 Lever-4
>
>
>
> ~~~~~~~~~
> SOLUTION:
>
> 1. Configure switches, on and off, as follows;
>
> SW-1 on
> SW-2 off
> SW-3 on
> SW-4 off
>
> 2. Open the door and record the on/off status of each light bulb.
>
> 3. Close the door and reconfigure the switches, on and off, as follows;
>
> SW-1 off
> SW-2 off
> SW-3 on
> SW-4 on
>
> 4. Open the door and record the on/off status of each light bulb.
>
> 5. From these collected data, one can calculate the particular one-to-one correspondence between switches and bulbs. In other words, which switch operates which bulb.
>
> John, to demonstrate that the algorithm works, randomly select a connection correspondence between switches and bulbs {e.g. (1, B), (2, C), (3, A), (4, D)}, and then, using your selected (secret) correspondence, determine which bulbs are lit in Steps 2 and 4 as instructed above. Send me (post) this information and, in return, I will tell you which switch operates which bulb.
>
> In other words, tell me which bulbs light when the switches are configured, firstly, as:
>
> SW-1 on
> SW-2 off
> SW-3 on
> SW-4 off
>
> And, secondly, as
>
> SW-1 off
> SW-2 off
> SW-3 on
> SW-4 on
>
> And, in return, I can tell you which switch operates which bulb.
>
> -- Ron
This is the end of the thread.
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