Friday Quiz - Help me wth a problem

[Quizmasters Apprentice]

A non wine quiz today, mainly because Quizmaster is dropping in tonight and I have to have the whole place spotless before he gets here, and the brooms are going on strike. Apparently they took a straw poll and in a clean sweep matters came to a head and they decided they wouldn’t handle anything for the rest of the day. I was bristling when I heard.

So here’s my problem.

The Castle was wired with electricity a year or so back, however due to the thickness of the stone there was some odd bits of cabling done.

There is a passage at the top of the spiral staircase in the castle. This passage has three standard lights are fitted to the walls. But the three switches for this lights are at the bottom of the spiral staircase. Each light connects to just one switch.

Quizmaster inhabits the area at the top of the staircase, I, as you could guess, live in the mouldy dank area at the bottom of the staircase. Being the lazy, mingy sot he is, Quizmaster yells down at me to switch on or off one or more of the lights, depending on what he’s up too, and I shudder to think what that is sometimes.

In my zeal to clean up the house I have knocked the labels off the switches that tell me which switche connects to which light. I can’t see whether lights are on or off from the bottom of the stairs, which is why Quizmaster yells. I’m thinking that by switching various combinations of lights on and then running up and down the stairs I’ll be able to work out which is which. I don’t like running up and down those stairs as I trip over my robes and I’m also not allowed to use magic.

Can tell me what is the least number of times I’d need to run up or down the stairs to figure out which switches work with which lights so I can reapply the labels and why. Each trip, up or down, counts as one.

[michaelw]

twice. once you find out the status of two of the switches, the 3rd one takes care of itself!

[GraemeG]

Hmm, I'm clearly missing sonething.It's got to be an even number of trips - either 2, 4 r 6. So:

Turn on 2 switches, up the stairs - now you know the dark light and the off-switch match.

Down the stairs - turn off one of the 2 switches. Up the stairs, check which light remains on - that was the switch you left on.

Back down the stairs to base - that makes four.

Trouble is, that matches the obvious way to do it, which is one switch turned on at a time. After going up and down twice like this, you know the control of all 3 switches. Still 4 trips.

You can't remove light bulbs? You've got to finish at the bottom? Can it be less than 4? But how?

Stumped for the moment,

cheers,
Graeme

[Quizmasters Apprentice]

No, both wrong,

Michael, by your twice I think you mean two trips up and down, which is four (up down up down).

Hmm, I'm clearly missing sonething.It's got to be an even number of trips - either 2, 4 r 6. So:
cheers,
Graeme

I don't have to finish at the bottom I only need to figure out which is which. I may chose to hang around upstairs and do more cleaning after I've got the answer.

No changing lightbulbs.

Noting I'll inevitably head back down the stairs at some stage to apply the labels, but that trip doesn't have to count as a turn.

[GraemeG]

I don't have to finish at the bottom

Which leads me to say 3 trips.

But I can't help feeling that you want us to get to one, somehow...

cheers,
Graeme

[Quizmasters Apprentice]

But I can't help feeling that you want us to get to one, somehow...

[Guest]

I say one trip.

DOWN the stairs to the cellar, pull out Quizmaster's favourite bottle of expensive red that should not be opened for twenty years, pull the cork, drink it down. And when Quizmaster rocks up tell him to stick his switches where the light don't shine.

[Quizmasters Apprentice]

DOWN the stairs to the cellar, pull out Quizmaster's favourite bottle of expensive red that should not be opened for twenty years, pull the cork, drink it down. And when Quizmaster rocks up tell him to stick his switches where the light don't shine.

An enticing suggestion, however the ILQ wouldn't qualify me after the apprenticeship finishes (it's in the contract).

On the other hand I could approach the LQI, they hate the members of the ILQ....

... in any case I still need the problem solved.

[Kieran]

OK, start at the top, with one or two lights already switched on.

Down to the bottom, to toggle one of the two lights that are of the same status.

Back to the top, to check which one you just changed.

I don't think I broke any rules. Two trips.

Kieran

[GraemeG]

Anything to do with the light switches having dimmers? Or timers? Cause it's easy in one trip then.

Otherwise, my brain's not nearly creative enought. Explains why I'm in beancounting not advertising...!

cheers,
Graeme

[david Morris]

Start at the switches downstairs. Turn one switch on, say for about 1 minute. Turn it off. Turn another switch on and go up the stairs. The warm globe will be the first switch, the lit globe will be the on switch and the rest follows!

Therefore one trip is needed.

I think.

[Quizmasters Apprentice]

OK, start at the top, with one or two lights already switched on.

Down to the bottom, to toggle one of the two lights that are of the same status.

Back to the top, to check which one you just changed.

I don't think I broke any rules. Two trips.

Kieran

Sorry Kieran,

Down at the bottom you still don't know which one of the two you've toggled. , unless you started toggling at the bottom.

[Quizmasters Apprentice]

Anything to do with the light switches having dimmers? Or timers? Cause it's easy in one trip then.

Otherwise, my brain's not nearly creative enought. Explains why I'm in beancounting not advertising...!

cheers,
Graeme

Dimmers, Timers?? They're expensive.

You're talking tightarse Quizmaster here.

Nope, standard switches and 40 watt globes.

[Quizmasters Apprentice]

Start at the switches downstairs. Turn one switch on, say for about 1 minute. Turn it off. Turn another switch on and go up the stairs. The warm globe will be the first switch, the lit globe will be the on switch and the rest follows!

Therefore one trip is needed.

I think.

BINGO!

The right answer, although with the length of the stairs I'd have it on for about 10 minutes. But that is the answer.

Now back to cleaning.

[Kieran]

OK, start at the top, with one or two lights already switched on.

Down to the bottom, to toggle one of the two lights that are of the same status.

Back to the top, to check which one you just changed.

I don't think I broke any rules. Two trips.

Kieran

Sorry Kieran,

Down at the bottom you still don't know which one of the two you've toggled. , unless you started toggling at the bottom.

I assume that, while you're at the bottom, you can tell which switches are on and which are off. I'm similarly assuming that I'm allowed to start at the top, with a light on already. (Say, I was up there cleaning when I had this great idea).

So, I start at the top with one light on.

I descend the stairs.

I can see which lightswitch is in the 'on' position.
I turn on one of the other lights.

I ascend the stairs.

I can see which light I've just turned on. By elimination, I can also determine which light the third switch connects to.

Two trips.

Kieran

[Quizmasters Apprentice]

I assume that, while you're at the bottom, you can tell which switches are on and which are off. I'm similarly assuming that I'm allowed to start at the top, with a light on already. (Say, I was up there cleaning when I had this great idea).

So, I start at the top with one light on.

I descend the stairs.

I can see which lightswitch is in the 'on' position.
I turn on one of the other lights.

I ascend the stairs.

I can see which light I've just turned on. By elimination, I can also determine which light the third switch connects to.

Two trips.

Kieran

All good thoughts Kieran but ultimately wrong. I just don't want to walk that far.

I'm taking David's apprach.

But while you're here checking some theories do some cleaning!!!.