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View Full Version : Weekend Riddle - fuse lines
You have two fuse lines (used to inflame an explosive at distance) The lines are even in size and they both burn completely in 60 minutes (each line burns completely in 60 minutes (edit P). But the burning of the lines is not even (eg 80% of the line can burn in 10 minutes so that the remaining 20% will burn 50 minutes))
Now your task: you get a lighter and you must meassure exactly 45 minutes while using the fuse lines and the lighter.
First good answer wins.
(1)
____60____
____60____
(2)
__30__ __30__
__30__ __30__
(3)
__30____30____30__ => ____90____ => __45__ __45__
(4)
and then entwine two 45min fuse lines to get one 45min fuse line.
Oor ... :bugeye: ?
one_raven 03-13-04, 05:10 AM But if the fuses are not uniform, cutting them in half will not necessarily get you 30 minutes.
Light the fuse and let it burn for fifteen minutes before putting it out.
kazakhan 03-13-04, 05:37 AM Join each fuse to the half way mark of the other...
one_raven 03-13-04, 05:41 AM Light the fuse and let it burn for fifteen minutes before putting it out.
How can you know how long 15 minutes is?
(he didn't say so, but I believe you don't have a timepiece)
Join each fuse to the half way mark of the other...
Again, if the fuses are not uniform, how would that be of any help?
kazakhan 03-13-04, 05:48 AM Not sure, but it's my best guess for now:D
one_raven 03-13-04, 05:59 AM I can't wait to find out.
I have seen this riddle before, but never the solution.
Ok, I misunderstood the riddle, but I think I've got it.
You light one fuse at both ends and light the other one at one end at the same time.
At the exact moment when the fuse lit at both ends is completely burned up you light the other end of the remaining fuse, when that completes it's burning process 45 minutes have passed since you first lit a fuse.
ie. The one lit at both ends burns for 30 minutes, leaving 30 minutes on the other fuse. And since you light the other end of that fuse it'll burn up in 15 minutes, giving you a total of 45 minutes.
one_raven 03-13-04, 06:13 AM Ok, I misunderstood the riddle, but I think I've got it.
You light one fuse at both ends and light the other one at one end at the same time.
At the exact moment when the fuse lit at both ends is completely burned up you light the other end of the remaining fuse, when that completes it's burning process 45 minutes have passed since you first lit a fuse.
ie. The one lit at both ends burns for 30 minutes, leaving 30 minutes on the other fuse. And since you light the other end of that fuse it'll burn up in 15 minutes, giving you a total of 45 minutes.
I think that's it.
Good call!!
DCLXVI wins. Good thinking!!
But the exposives didn't go off :(
But the exposives didn't go off :(
Well, (it wasn't the point of the riddle) but since you brought it up:
the system (as described above) could be used to ignite the explosives by using a light sensor. Such sensor would go off when the light of the burning lines would die down.
But the sensor would have to be used twice....so it would be more efficient to use some other way... :)
one_raven 03-13-04, 12:57 PM The version I heard wasn't a fuse and explosives.
It was two lengths of rope and you had no watch, just the lengths of rope and a lighter, but needed to time 45 minutes.
Rappaccini 03-13-04, 01:57 PM Sometimes in Bio class my friends and I tell riddles to one another. I remember this one, or at least the rope-length verson of it.
A friend of mine was able to get it in 'bout two minutes time. I was impressed, needless to say.
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