View Full Version : Rope puzzle

23rd Aug 2001, 19:16
For those of you looking to exercise your mind...

You have two ropes, not necessarily the same length. You also have a box of matches.

Neither rope burns at an even rate along its length. All you can be certain of is that each rope would take one hour to burn completely.

How do you measure a 45 minute interval?

Time limit: five minutes!

23rd Aug 2001, 19:33
Use a clock :rolleyes:

23rd Aug 2001, 19:38
Light the first rope at both ends. At the same time light the second rope at one end only.

After 30 minutes the first rope is completely gone, and the second rope has 30 minutes left. Light the second end of the second rope which will now fizzle at both ends for 15 minutes. Total 45.

Next !!

23rd Aug 2001, 19:39
Put fire to one rope in both ends, when that rope has burned 30 min have passed.

Cut the second rope in half and put fire to all four ends. When one half has burned, cut the other half in half and put fire to the new ends, i e keep four rope ends burning at all times. When that rope is gone too, an additional 15 minutes will have gone by.

That's the solution you were looking for?


You want it when?
23rd Aug 2001, 19:49
Lay out the ropes so that they form a clock-face on the ground.

Then open the match box and remove one match, close the box and replace the match so that the match is sticking up - like a walkie-talkie ariel. Then place the match box near the mouth and say...

"Dagger one-natural, Dagger one-natural, time check"
Someone will reply and tell you the time

Repeat the process, moving the bits of rope to the new time until 45 minutes have elapsed.

Sheesh, simple ;)

23rd Aug 2001, 19:50
just as I was feeling sort of smart... of course you had to spoil it! :D


23rd Aug 2001, 20:04
That's OK ft - your solution had a sort of recursive charm to it :D

tony draper
23rd Aug 2001, 20:21
When my Port Said watch stops,which happens quite often, I simply write the time down on a piece of paper before I leave the house.

23rd Aug 2001, 20:23
I find that carrying a sun-dial around with me works quite well.


tony draper
23rd Aug 2001, 20:27
You have a sheep, a bag of cabbages, and a wolf, you come to a wide river , a boat is tied up at the side of this river, but said boat , only allows you to take two of these items across at a time.
You cannot carry the sheep and the wolf together, because the wolf will eat the sheep,nor can you leave them on the bank together or the same thing will happen, same for the sheep and the bag of cabbages, if left alone the sheep will eat the cabbages.
What is the least number of journeys to bring your cargo safely to the far bank.

Err don't think I got that right somehow.
I think you cant leave the sheep or wolf alone or they run away

[ 23 August 2001: Message edited by: tony draper ]

23rd Aug 2001, 20:42
If you can't leave either of'em alone it gets a wee bit impossible. At one time, you have to be in the boat with the cabbage, meaning either the sheep or the wolf can't be in the boat and will be alone.

Otherwise, bring the wolf and the cabbage across, then go back for the sheep.

Or let the sheep eat the cabbage, take the sheep and the wolf across, then eat the sheep when you were going to eat the cabbage, sell the wolf skin and buy a new sheep. ;)

/ft, waiting for Grainger to shoot him down in flames again :D

You want it when?
23rd Aug 2001, 20:42
FFF - The sun dial idea is fine, I had a fold up one on my right wrist for a while. The only problem is you need a compass to allign it and a wrist watch to verify the calibration.

23rd Aug 2001, 20:48
FFF, I did the sundial thing for a while too. Even attached a flashlight to the frame so I could see to read it at night. Only then did I find out that I had been had. Apparently they had sold me some cheap, solar powered version. It always stopped at night. :(


23rd Aug 2001, 21:28
Almost got it ft: you just left the bit out where before you go across with the wolf and cabbage, you sh*g the sheep stupid so it can't run away :eek:

23rd Aug 2001, 21:32
Oh, so you think that's a bit raw, eh?

Well let me tell you, no way am I going to sh*g a bag of cabbages - and if you want to have a go at the wolf, you're a braver man than I ;)

tony draper
23rd Aug 2001, 21:38
Yeh I think I got it wrong somehow, can't find the book now.
(mind games for the super intelligent)
not much of a plot that book, I'm supprised at you Mr G,
I thought you was a fizzysist.

Onan the Clumsy
23rd Aug 2001, 21:41
I used to have a book called...erm... "How to develop a super power memory"

I got halfway through it and left it on the bus :rolleyes:

23rd Aug 2001, 22:31
"Hey Rocky! Watch me pull a Rabbit outta my hat!"


24th Aug 2001, 01:21
drapes, I think the answer is you can only take one item at a time, so you have to take the sheep first and leave (wolf + cabbage), then you leave the sheep on the far side, go back, take the wolf over, bring the sheep back, leave the sheep and take the cabbage over ah f*ck it you get the idea.....

[ 23 August 2001: Message edited by: Grainger ]