Can You Solve This Clever Puzzle?

I hate myself for failing to see the solution to this ... :evil:

Suppose that you have two fuses, each of which takes an hour to burn from one end to the other, and as many matches as you need.

Describe how you can use the fuses to time a period of 45 minutes.

Trivial? There's a catch, though: The fuses burn at irregular rates, so you can't, for example, just cut a quarter off one of the fuses. All you can assume is that each fuse has a "burn time" of one hour.

If nobody has posted an answer in a few minutes, I'll edit this message and add the answer in a "spoiler" section. No Googling allowed!!!

[spoiler] Simultaneously light one fuse at both ends and the other at just one end. When the first fuse burns out, light the second fuse at the other end too. When the second fuse has burnt out, 45 minutes will have elapsed. [/spoiler]

I have an idea, but it involves the use of a stopwatch >_>

I have an idea, but it involves the use of a stopwatch >_>

Alternatively you could just wait until 3/4 of a fuse has been burnt.

Funky_Llama

I have an idea, but it involves the use of a stopwatch >_>

Alternatively you could just wait until 3/4 of a fuse has been burnt.

Funky_Llama

Sorry, no stopwatches allowed. Matches only. (Or a cigarette lighter, if you prefer.) :P

[QUOTE="Funky_Llama"]

I have an idea, but it involves the use of a stopwatch >_>

Alternatively you could just wait until 3/4 of a fuse has been burnt.

xaos

I'm assuming the fact that there is two fuses has something to with it, but I have no conclusive answer.

Ignore the matches and the fuses and count of 2700 seconds.xaos

What if I light one end of the fuse first, then the other end when the other side has reached the centre of the fuse?super_mario_128

Cut them both in half - then in half again. Now each should burn 15minutes each !!

imo the problem is very poorly worded and bad wording ruins puzzles to me.

wtf does "iregular burn times" even mean? its like a deus-ex machina clause just to create fake difficulty in the puzzle.

[QUOTE="super_mario_128"]What if I light one end of the fuse first, then the other end when the other side has reached the centre of the fuse?Funky_Llama

I would light the matches and let it burn. Time how long a match takes to burn and since I have unlimited matches I would keep doing it until it reached 45 minutes. The fuses are irrelevant!

I hate myself for failing to see the solution to this ... :evil:

Suppose that you have two fuses, each of which takes an hour to burn from one end to the other, and as many matches as you need.

Describe how you can use the fuses to time a period of 45 minutes.

Trivial? There's a catch, though: The fuses burn at irregular rates, so you can't, for example, just cut a quarter off one of the fuses. All you can assume is that each fuse has a "burn time" of one hour.

If nobody has posted an answer in a few minutes, I'll edit this message and add the answer in a "spoiler" section. No Googling allowed!!!

Stesilaus

Cut them both in half - then in half again. Now each should burn 15minutes each !!

imo the problem is very poorly worded and bad wording ruins puzzles to me. JPOBS

It may seem so, but you actually have all the information you need!

[QUOTE="JPOBS"]imo the problem is very poorly worded and bad wording ruins puzzles to me. Stesilaus

It may seem so, but you actually have all the information you need!

Count how many matches you can burn in the time it takes to burn one fuse fully, then multiply that number by .75 and burn that many matches.

I don't really understand the question. If it takes exactly one hour for the fuses to burn completely, but they burn at irregular rates, the you'd first have to determine the rates at which they burn; since that doesn't appear possible, could it have something to do with criss-crossing the fuses together?

[QUOTE="JPOBS"]imo the problem is very poorly worded and bad wording ruins puzzles to me. Stesilaus

It may seem so, but you actually have all the information you need!

Does each fuse burn at the same irregular rate?KHAndAnime

No. Each can be burning at any speed at any point along its length. But each has exactly one hour of total burn time.

[QUOTE="Stesilaus"]

[QUOTE="JPOBS"]imo the problem is very poorly worded and bad wording ruins puzzles to me. JPOBS

It may seem so, but you actually have all the information you need!

I agree; the way it's worded makes it very confusing.

[QUOTE="KHAndAnime"]Does each fuse burn at the same irregular rate?Stesilaus

No. Each can be burning at any speed at any point along its length. But each has exactly one hour of total burn time.

There's a math formula to solve this, but I can't remember what it is.

imo the problem is very poorly worded and bad wording ruins puzzles to me.

wtf does "iregular burn times" even mean? its like a deus-ex machina clause just to create fake difficulty in the puzzle.

JPOBS

Meaning, that one quarter of the fuse wouldnt necessarily take exactly 15 minutes to burn. The first quarter of it could burn in 5 minutes, the next in 15, the next in 10, and the last in 30. Get it? Either way, I have no clue.

[QUOTE="Stesilaus"]

[QUOTE="KHAndAnime"]Does each fuse burn at the same irregular rate?Theokhoth

No. Each can be burning at any speed at any point along its length. But each has exactly one hour of total burn time.

There's a math formula to solve this, but I can't remember what it is.

[QUOTE="JPOBS"]

imo the problem is very poorly worded and bad wording ruins puzzles to me.

wtf does "iregular burn times" even mean? its like a deus-ex machina clause just to create fake difficulty in the puzzle.

KcurtorMas

Meaning, that one quarter of the fuse wouldnt necessarily take exactly 15 minutes to burn. The first quarter of it could burn in 5 minutes, the next in 15, the next in 10, and the last in 30. Get it? Either way, I have no clue.

[QUOTE="Stesilaus"]

[QUOTE="KHAndAnime"]Does each fuse burn at the same irregular rate?Theokhoth

No. Each can be burning at any speed at any point along its length. But each has exactly one hour of total burn time.

There's a math formula to solve this, but I can't remember what it is.

[QUOTE="JPOBS"][QUOTE="Stesilaus"]

It may seem so, but you actually have all the information you need!

Theokhoth

I agree; the way it's worded makes it very confusing.

OK, here's a better wording:

Each fuse takes an hour to burn out.

But the flame doesn't proceed along the fuse at a constant, predictable rate. It could take 10 minutes to burn the first inch, 5 minutes to burn the second inch, 20 minutes to burn the third inch, etc.

You don't know anything about the burn rate, other than that each fuse takes one hour to burn completely.

I hate myself for failing to see the solution to this ... :evil:

Suppose that you have two fuses, each of which takes an hour to burn from one end to the other, and as many matches as you need.

Describe how you can use the fuses to time a period of 45 minutes.

Trivial? There's a catch, though: The fuses burn at irregular rates, so you can't, for example, just cut a quarter off one of the fuses. All you can assume is that each fuse has a "burn time" of one hour.

If nobody has posted an answer in a few minutes, I'll edit this message and add the answer in a "spoiler" section. No Googling allowed!!!

Stesilaus

[spoiler] Lightboth ends offuse one and one end of fuse two at the same time.Light the other end of fuse two at the exact same time fuse one burns up. When fuse two is finished burning, 45 minutes will havepassed [/spoiler]

I may have an idea.

If you cross the fuses together like in a DNA strand, and light them both at the same time, then one or the other will reach the intersecting point, thus lighting the other fuse at that point before the slower fuse gets there. At that point, fuses will be travelling up the DNA strand, and each time one of them reaches an intersecting point, both fuses will light at that point. If you time each lighting of each intersection, you might be able to get forty-five minutes.

That's just an idea. It looks good on the paper I drew.

[spoiler] Using a spoiler because my friend told me the answer. Is it that you light both ends of the first fuse, and the second fuse at the same time. Then, after the first fuse burns completely, you know that's half an hour. Light the other end of the second fuse, and when it burns out, it'll be exactly 3/4 of an hour since you started the first fuse. Am I right? [/spoiler] LZ71

[spoiler] Using a spoiler because my friend told me the answer. Is it that you light both ends of the first fuse, and the second fuse at the same time. Then, after the first fuse burns completely, you know that's half an hour. Light the other end of the second fuse, and when it burns out, it'll be exactly 3/4 of an hour since you started the first fuse. Am I right? [/spoiler] LZ71

You beat me to it.

[QUOTE="LZ71"][spoiler] Using a spoiler because my friend told me the answer. Is it that you light both ends of the first fuse, and the second fuse at the same time. Then, after the first fuse burns completely, you know that's half an hour. Light the other end of the second fuse, and when it burns out, it'll be exactly 3/4 of an hour since you started the first fuse. Am I right? [/spoiler] super_mario_128

Yes, LZ71, you got it right! ;)

I'll add the solution to the original message in a spoiler section.

[QUOTE="Stesilaus"]

I hate myself for failing to see the solution to this ... :evil:

Suppose that you have two fuses, each of which takes an hour to burn from one end to the other, and as many matches as you need.

Describe how you can use the fuses to time a period of 45 minutes.

Trivial? There's a catch, though: The fuses burn at irregular rates, so you can't, for example, just cut a quarter off one of the fuses. All you can assume is that each fuse has a "burn time" of one hour.

If nobody has posted an answer in a few minutes, I'll edit this message and add the answer in a "spoiler" section. No Googling allowed!!!

psychobrew

Answer

It took me a minute to get it, but this is correct.

You light the first fuse at both ends, and light the other at one end. The first, being lit at both ends, burns for approximately 30 minutes, and also leaves the other fuse lit at one end with 30 minutes left to burn. Once the first fuse is completely burnt out, light the other end of the second fuse, cutting 30 minutes into 15, thus having a total of 45 minutes.

Damn, too late. Oh well, my answer is explained better...which makes me win in my own mind!!!

I hate myself for failing to see the solution to this ... :evil:

Suppose that you have two fuses, each of which takes an hour to burn from one end to the other, and as many matches as you need.

Describe how you can use the fuses to time a period of 45 minutes.

Trivial? There's a catch, though: The fuses burn at irregular rates, so you can't, for example, just cut a quarter off one of the fuses. All you can assume is that each fuse has a "burn time" of one hour.

If nobody has posted an answer in a few minutes, I'll edit this message and add the answer in a "spoiler" section. No Googling allowed!!!

Stesilaus

ANSWER

Light one fuse on both ends. When it finishes you should have (30 minutes)

Take the other fuse and cut it in half and light both ends of each half. When that fuse is all burned up 15 minutes should have passed. (15 minutes)

Congrats to the people who got it right. I've added the solution to a spoiler section in the original posting.

I first found the puzzle on Grand Illusions. The site also has some very cool optical illusions, novelty toys, etc. and is worth a look IMHO.

YESSS! Figured it out myself, I feel so proud. :D

THE answer is apple pie....that's the answer to everything