Conundrums, Puzzles, Logic Problems (1 Viewer)

[fatguyinalittlecoat]

Why don't we have any of these anymore? It has to be at least a year since we've done anything like the monks with dots on their heads or the 12 balls on the scale, or one of those stories where you have to figure out what happened by asking yes/no questions. Is it because of our Smoolessness?

Anybody have anything?

 

[SKribbles]

Didn't think there was much logic in the FFA.

 

[The Man from Laramie]

What if D-O-G really spelled "cat?"

 

[Challenge Everything]

http://img124.imageshack.us/my.php?image=trigridzc2.gif

Explain this one.

 

[LT21]

Why don't we have any of these anymore? It has to be at least a year since we've done anything like the monks with dots on their heads or the 12 balls on the scale, or one of those stories where you have to figure out what happened by asking yes/no questions. Is it because of our Smoolessness?Anybody have anything?

I missed the 12 balls on the scale and the monks with dots on their heads.Can you put them here again?

 

[RudiStein]

http://img124.imageshack.us/my.php?image=trigridzc2.gif

Explain this one.

Oh the humanity.

 

[fatguyinalittlecoat]

It reminds me of this story ...

 

[fatguyinalittlecoat]

Why don't we have any of these anymore? It has to be at least a year since we've done anything like the monks with dots on their heads or the 12 balls on the scale, or one of those stories where you have to figure out what happened by asking yes/no questions. Is it because of our Smoolessness?Anybody have anything?

I missed the 12 balls on the scale and the monks with dots on their heads.Can you put them here again?

I don't think I really want to. I want some new stuff.

 

[bostonfred]

There are two lengths of rope.

Each one can burn in exactly one hour.

They are not necessarily of the same length or width as each other.

They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.

By burning the ropes, how do you measure exactly 45 minutes worth of time?

 

[The Man from Laramie]

http://img124.imageshack.us/my.php?image=trigridzc2.gif

Explain this one.

link to answer

 

[parasaurolophus]

http://img124.imageshack.us/my.php?image=trigridzc2.gif

Explain this one.

Oh the humanity.

lolshuke can explain it

 

[The Man from Laramie]

There are two lengths of rope.Each one can burn in exactly one hour.They are not necessarily of the same length or width as each other.They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.By burning the ropes, how do you measure exactly 45 minutes worth of time?

you forgot to mention that the time between lighting ends is insignificant.I got asked this question in a Goldman Sachs interview about 5 years ago.

 

[fatguyinalittlecoat]

There are two lengths of rope.

Each one can burn in exactly one hour.

They are not necessarily of the same length or width as each other.

They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.

By burning the ropes, how do you measure exactly 45 minutes worth of time?

mytagid = Math.floor( Math.random() * 100 );document.write("1. Light both sides of rope 1 and one side of rope 2.

2. When rope 1 burns out, 30 minutes have elapsed, so the rope 2 has 30 minutes left

3. Light other side of rope 2.

4. When rope 2 burns out, 45 minutes total have elapsed.

*** SPOILER ALERT! Click this link to display the potential spoiler text in this box. ***

");document.close();

 

[Sweet J]

There are two lengths of rope.Each one can burn in exactly one hour.They are not necessarily of the same length or width as each other.They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.By burning the ropes, how do you measure exactly 45 minutes worth of time?

Off the top of my head:I'd light both ends of one rope (1/2 hour). When that is done, I'd cut the other rope in 1/2, then light both ends of each of the pieces (15 min)

 

[fatguyinalittlecoat]

If somebody doesn't post some new material in here soon, we're gonna have to bust out the Monty Hall problem. Don't make me do it.

 

[parasaurolophus]

There are two lengths of rope.Each one can burn in exactly one hour.They are not necessarily of the same length or width as each other.They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.By burning the ropes, how do you measure exactly 45 minutes worth of time?

you forgot to mention that the time between lighting ends is insignificant.I got asked this question in a Goldman Sachs interview about 5 years ago.

this seems kind of like a silly interview question.we used to ask a question about a ficticious situation that really didnt have an answer just to see if after throwing out more details would get them to change their answer. The answer was irrelevant, it was their reaction to the pushing and prodding.Did they later tell you the purpose in asking this question?

 

[parasaurolophus]

its not a great one, but my sister emailed it to me a while back...

A man has to get a fox, a chicken, and a sack of corn across a river. He has a rowboat, and it can only carry him and one other thing at a time. If the fox and the chicken are left together, the fox will eat the chicken. If the chicken and the corn is left together, the chicken will eat the corn. How does the man do it?

 

[The Man from Laramie]

There are two lengths of rope.Each one can burn in exactly one hour.They are not necessarily of the same length or width as each other.They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.By burning the ropes, how do you measure exactly 45 minutes worth of time?

you forgot to mention that the time between lighting ends is insignificant.I got asked this question in a Goldman Sachs interview about 5 years ago.

this seems kind of like a silly interview question.we used to ask a question about a ficticious situation that really didnt have an answer just to see if after throwing out more details would get them to change their answer. The answer was irrelevant, it was their reaction to the pushing and prodding.Did they later tell you the purpose in asking this question?

A lot of places ask brain teasers in interviews. That's most of what an entire day of interviewing at Microsoft (which I also did at one point) is. The whole point is that they want insight into your problem solving skills and ability to perform under pressure.Worst interview question I ever had (but an internship I was offered and took) was with HP. It was a phone interview, and the guy was literally describing electric circuits to me over the phone and asking me to describe the transient and steady state responses.

 

[fatguyinalittlecoat]

A lot of places ask brain teasers in interviews. That's most of what an entire day of interviewing at Microsoft (which I also did at one point) is.

So you spent an entire day doing brain teasers, yet you have contributed none to this thread?

 

[Dragons]

http://img124.imageshack.us/my.php?image=trigridzc2.gif

Explain this one.

 

[The Man from Laramie]

If somebody doesn't post some new material in here soon, we're gonna have to bust out the Monty Hall problem. Don't make me do it.

What's the Monty Hall problem, and why would anyone switch doors?

 

[SoCalBroncoFan]

There are two lengths of rope.Each one can burn in exactly one hour.They are not necessarily of the same length or width as each other.They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.By burning the ropes, how do you measure exactly 45 minutes worth of time?

Off the top of my head:I'd light both ends of one rope (1/2 hour). When that is done, I'd cut the other rope in 1/2, then light both ends of each of the pieces (15 min)

Wow. Impressive.My answer was going to be to use a watch.

 

[parasaurolophus]

There are two lengths of rope.Each one can burn in exactly one hour.They are not necessarily of the same length or width as each other.They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.By burning the ropes, how do you measure exactly 45 minutes worth of time?

you forgot to mention that the time between lighting ends is insignificant.I got asked this question in a Goldman Sachs interview about 5 years ago.

this seems kind of like a silly interview question.we used to ask a question about a ficticious situation that really didnt have an answer just to see if after throwing out more details would get them to change their answer. The answer was irrelevant, it was their reaction to the pushing and prodding.Did they later tell you the purpose in asking this question?

A lot of places ask brain teasers in interviews. That's most of what an entire day of interviewing at Microsoft (which I also did at one point) is. The whole point is that they want insight into your problem solving skills and ability to perform under pressure.Worst interview question I ever had (but an internship I was offered and took) was with HP. It was a phone interview, and the guy was literally describing electric circuits to me over the phone and asking me to describe the transient and steady state responses.

i guess I should have asked what the jobs were. I made the mistake of assuming a broker position. But if you interviewed with microsoft also, probably not a broker interview

 

[Green and Gold]

Take the chicken across, drop it off. Then take the fox across, pick up the chicken, row back, drop off the chicken, pick up the corn, row across, drop off the corn, then go back for the chicken.

 

[SoCalBroncoFan]

its not a great one, but my sister emailed it to me a while back...A man has to get a fox, a chicken, and a sack of corn across a river. He has a rowboat, and it can only carry him and one other thing at a time. If the fox and the chicken are left together, the fox will eat the chicken. If the chicken and the corn is left together, the chicken will eat the corn. How does the man do it?

Too easy.1st trip across = Chicken2nd trip = CornReturn trip = bring chicken back2nd trip across = foxreturn trip = nothing3rd trip across = chicken

 

[Peyton Marino]

there's a magical island that is populated by 99 dragons. all of these dragons have red eyes, but they do not know this. if at any time it is possible for a dragon to deduce his eye color, the dragon will die the next day at noon. dragons, being the intelligent creatures they are, never discuss eye colors and they avoid looking in water where they might accidentally see their reflection. dragons are also extremely observant, so each dragon knows that the other 98 have red eyes. one day, an evil logician appears on the island and gathers the dragons together. he yells to them, "there is at least one dragon with red eyes on this island!" and suddenly vanishes. the dragons freak out as eye colors are not supposed to be discussed on the island, but eventually they settle down upon seeing many other dragons with red eyes. 99 days later, 99 dragons are dead at noon. why?

 

[fatguyinalittlecoat]

If we ever get a good puzzle in here, we should try to use spoiler tags. The rowboat one was easy, so no big deal.

 

[Dragons]

there's a magical island that is populated by 99 dragons. all of these dragons have red eyes, but they do not know this. if at any time it is possible for a dragon to deduce his eye color, the dragon will die the next day at noon. dragons, being the intelligent creatures they are, never discuss eye colors and they avoid looking in water where they might accidentally see their reflection. dragons are also extremely observant, so each dragon knows that the other 98 have red eyes. one day, an evil logician appears on the island and gathers the dragons together. he yells to them, "there is at least one dragon with red eyes on this island!" and suddenly vanishes. the dragons freak out as eye colors are not supposed to be discussed on the island, but eventually they settle down upon seeing many other dragons with red eyes. 99 days later, 99 dragons are dead at noon. why?

This is the same premise as the monk one.

 

[shuke]

its not a great one, but my sister emailed it to me a while back...A man has to get a fox, a chicken, and a sack of corn across a river. He has a rowboat, and it can only carry him and one other thing at a time. If the fox and the chicken are left together, the fox will eat the chicken. If the chicken and the corn is left together, the chicken will eat the corn. How does the man do it?

Take the chicken over.Go back.Take the fox over.Go back with the chicken and leave it there.Take the corn over.Then go back and get the chicken.

 

[Peyton Marino]

there's a magical island that is populated by 99 dragons. all of these dragons have red eyes, but they do not know this. if at any time it is possible for a dragon to deduce his eye color, the dragon will die the next day at noon. dragons, being the intelligent creatures they are, never discuss eye colors and they avoid looking in water where they might accidentally see their reflection. dragons are also extremely observant, so each dragon knows that the other 98 have red eyes. one day, an evil logician appears on the island and gathers the dragons together. he yells to them, "there is at least one dragon with red eyes on this island!" and suddenly vanishes. the dragons freak out as eye colors are not supposed to be discussed on the island, but eventually they settle down upon seeing many other dragons with red eyes. 99 days later, 99 dragons are dead at noon. why?

This is the same premise as the monk one.

sorry, never saw the monk one.

 

[RedmondLonghorn]

There is this thing called the Wesson Selection Test that I heard about somewhere. Apparently, if you do well on it you are pretty bright. Unfortunately, you are also likely to be a psycho.

 

[Dragons]

there's a magical island that is populated by 99 dragons. all of these dragons have red eyes, but they do not know this. if at any time it is possible for a dragon to deduce his eye color, the dragon will die the next day at noon. dragons, being the intelligent creatures they are, never discuss eye colors and they avoid looking in water where they might accidentally see their reflection. dragons are also extremely observant, so each dragon knows that the other 98 have red eyes. one day, an evil logician appears on the island and gathers the dragons together. he yells to them, "there is at least one dragon with red eyes on this island!" and suddenly vanishes. the dragons freak out as eye colors are not supposed to be discussed on the island, but eventually they settle down upon seeing many other dragons with red eyes. 99 days later, 99 dragons are dead at noon. why?

This is the same premise as the monk one.

sorry, never saw the monk one.

no problem, it's a good puzzle if you don't already know how to solve it.

 

[Commish77]

its not a great one, but my sister emailed it to me a while back...A man has to get a fox, a chicken, and a sack of corn across a river. He has a rowboat, and it can only carry him and one other thing at a time. If the fox and the chicken are left together, the fox will eat the chicken. If the chicken and the corn is left together, the chicken will eat the corn. How does the man do it?

How does he keep them from eating each other even before they need to be transported?

 

[parasaurolophus]

its not a great one, but my sister emailed it to me a while back...A man has to get a fox, a chicken, and a sack of corn across a river. He has a rowboat, and it can only carry him and one other thing at a time. If the fox and the chicken are left together, the fox will eat the chicken. If the chicken and the corn is left together, the chicken will eat the corn. How does the man do it?

How does he keep them from eating each other even before they need to be transported?

put the corn in your pants to look like a FBG and put the chicken above your head.

 

[badmojo1006]

I have 2 coins in my hand that total 30 cents. One is not a nickel. What are they?

 

[Commish77]

I have 2 coins in my hand that total 30 cents. One is not a nickel. What are they?

 

[Peyton Marino]

Achmed and Ali are camel-drivers and on one day they decided to quit their job. They wanted to become shepherds. So they went to the market and sold all their camels. The amount of money(dinars) they received for each camel is the same as the total of camels they owned. For that money they bought as many sheep as possible at 10 dinars a sheep. For the money that was left they bought a goat.

On their way home they got in a fight and decided to split up. When they divided the sheep there was one sheep left. So Ali said to Achmed "I take the last sheep and you can get the goat". "That's not fair" said Achmed, "a goat costs lesser than a sheep". "Ok", Ali said "then I will give you one of my dogs and then we are even". And Achmed agreed.

What costs a dog?

 

[videoguy505]

There are two lengths of rope.Each one can burn in exactly one hour.They are not necessarily of the same length or width as each other.They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.By burning the ropes, how do you measure exactly 45 minutes worth of time?

Off the top of my head:I'd light both ends of one rope (1/2 hour). When that is done, I'd cut the other rope in 1/2, then light both ends of each of the pieces (15 min)

Wow. Impressive.My answer was going to be to use a watch.

Cutting the second rope in half won't necessarily equal 15 minutes, though, because they aren't uniform width. The second rope may have one half burning faster than the other... lighting the halves could burn each half out in 10 and 20 minutes, for example.

 

[The Man from Laramie]

There are two lengths of rope.Each one can burn in exactly one hour.They are not necessarily of the same length or width as each other.They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.By burning the ropes, how do you measure exactly 45 minutes worth of time?

Off the top of my head:I'd light both ends of one rope (1/2 hour). When that is done, I'd cut the other rope in 1/2, then light both ends of each of the pieces (15 min)

Wow. Impressive.My answer was going to be to use a watch.

Cutting the second rope in half won't necessarily equal 15 minutes, though, because they aren't uniform width. The second rope may have one half burning faster than the other... lighting the halves could burn each half out in 10 and 20 minutes, for example.

He was really close. You don't need to cut it in half. You light both ends of rope 1 and one end of rope 2. When rope 1 burns out, you light the other end of rope 2. Regardless or non-uniformity in the thickness, it will burn out in exactly 45 minutes.

 

[parasaurolophus]

there's a magical island that is populated by 99 dragons. all of these dragons have red eyes, but they do not know this. if at any time it is possible for a dragon to deduce his eye color, the dragon will die the next day at noon. dragons, being the intelligent creatures they are, never discuss eye colors and they avoid looking in water where they might accidentally see their reflection. dragons are also extremely observant, so each dragon knows that the other 98 have red eyes. one day, an evil logician appears on the island and gathers the dragons together. he yells to them, "there is at least one dragon with red eyes on this island!" and suddenly vanishes. the dragons freak out as eye colors are not supposed to be discussed on the island, but eventually they settle down upon seeing many other dragons with red eyes. 99 days later, 99 dragons are dead at noon. why?

 

[Peyton Marino]

there's a magical island that is populated by 99 dragons. all of these dragons have red eyes, but they do not know this. if at any time it is possible for a dragon to deduce his eye color, the dragon will die the next day at noon. dragons, being the intelligent creatures they are, never discuss eye colors and they avoid looking in water where they might accidentally see their reflection. dragons are also extremely observant, so each dragon knows that the other 98 have red eyes. one day, an evil logician appears on the island and gathers the dragons together. he yells to them, "there is at least one dragon with red eyes on this island!" and suddenly vanishes. the dragons freak out as eye colors are not supposed to be discussed on the island, but eventually they settle down upon seeing many other dragons with red eyes. 99 days later, 99 dragons are dead at noon. why?

 

[videoguy505]

there's a magical island that is populated by 99 dragons. all of these dragons have red eyes, but they do not know this. if at any time it is possible for a dragon to deduce his eye color, the dragon will die the next day at noon. dragons, being the intelligent creatures they are, never discuss eye colors and they avoid looking in water where they might accidentally see their reflection. dragons are also extremely observant, so each dragon knows that the other 98 have red eyes. one day, an evil logician appears on the island and gathers the dragons together. he yells to them, "there is at least one dragon with red eyes on this island!" and suddenly vanishes. the dragons freak out as eye colors are not supposed to be discussed on the island, but eventually they settle down upon seeing many other dragons with red eyes. 99 days later, 99 dragons are dead at noon. why?

mytagid = Math.floor( Math.random() * 100 );document.write("Sounds good to me. If after 1 day, 1 dragon saw 98 pairs of, say, blue eyes, he'd know he was the one with red eyes, and die. This didn't happen. So the dragons know that there are at least 2 dragons with red eyes. On day 2, if a dragon saw 97 blue eyed dragons and 1 red eyed dragon, he'd know he was the other red eyed dragon and die. This didn't happen, so they know there must be at least 3 dragons with red eyes. Repeat.

*** SPOILER ALERT! Click this link to display the potential spoiler text in this box. ***

");document.close();

 

[The Man from Laramie]

there's a magical island that is populated by 99 dragons. all of these dragons have red eyes, but they do not know this. if at any time it is possible for a dragon to deduce his eye color, the dragon will die the next day at noon. dragons, being the intelligent creatures they are, never discuss eye colors and they avoid looking in water where they might accidentally see their reflection. dragons are also extremely observant, so each dragon knows that the other 98 have red eyes. one day, an evil logician appears on the island and gathers the dragons together. he yells to them, "there is at least one dragon with red eyes on this island!" and suddenly vanishes. the dragons freak out as eye colors are not supposed to be discussed on the island, but eventually they settle down upon seeing many other dragons with red eyes. 99 days later, 99 dragons are dead at noon. why?

####### logicians have to ruin LarryBoy's fun.

 

[Peyton Marino]

there's a magical island that is populated by 99 dragons. all of these dragons have red eyes, but they do not know this. if at any time it is possible for a dragon to deduce his eye color, the dragon will die the next day at noon. dragons, being the intelligent creatures they are, never discuss eye colors and they avoid looking in water where they might accidentally see their reflection. dragons are also extremely observant, so each dragon knows that the other 98 have red eyes. one day, an evil logician appears on the island and gathers the dragons together. he yells to them, "there is at least one dragon with red eyes on this island!" and suddenly vanishes. the dragons freak out as eye colors are not supposed to be discussed on the island, but eventually they settle down upon seeing many other dragons with red eyes. 99 days later, 99 dragons are dead at noon. why?

mytagid = Math.floor( Math.random() * 100 );document.write("Sounds good to me. If after 1 day, 1 dragon saw 98 pairs of, say, blue eyes, he'd know he was the one with red eyes, and die. This didn't happen. So the dragons know that there are at least 2 dragons with red eyes. On day 2, if a dragon saw 97 blue eyed dragons and 1 red eyed dragon, he'd know he was the other red eyed dragon and die. This didn't happen, so they know there must be at least 3 dragons with red eyes. Repeat.

*** SPOILER ALERT! Click this link to display the potential spoiler text in this box. ***

");document.close();

mytagid = Math.floor( Math.random() * 100 );document.write("actually, the dragons know that there are at least 98 other dragons on the island with red eyes. they can see them. look at it as if there are two dragons on the island. they both have red eyes. when the logician appears and says "at least one of you MFers has red eyes" each dragon assumes it's the other dragon that has red eyes and assume that they themselves have blue eyes. if it is true that one of those dragons had blue eyes, then the other dragon would see those blue eyes and know he has red eyes, then he'd be dead the next day...

but, both dragons have red eyes, and they can see the other has red eyes. therefore, when neither of them dies on the first day, it is impossible that either of the dragons have blue eyes, because neither of them died. so they both die.

now, just extrapolate that out with 99 dragons.*** SPOILER ALERT! Click this link to display the potential spoiler text in this box. ***

");document.close();

 

[Mungo Burrows]

Achmed and Ali are camel-drivers and on one day they decided to quit their job. They wanted to become shepherds. So they went to the market and sold all their camels. The amount of money(dinars) they received for each camel is the same as the total of camels they owned. For that money they bought as many sheep as possible at 10 dinars a sheep. For the money that was left they bought a goat.

On their way home they got in a fight and decided to split up. When they divided the sheep there was one sheep left. So Ali said to Achmed "I take the last sheep and you can get the goat". "That's not fair" said Achmed, "a goat costs lesser than a sheep". "Ok", Ali said "then I will give you one of my dogs and then we are even". And Achmed agreed.

What costs a dog?

mytagid = Math.floor( Math.random() * 100 );document.write("Pretty sure the dog costs 2 dinar

I'm pretty sure the only squares (#camels * cost of camels) with an odd whole multiple of 10 have a remainder of 6 (36, 196, 256, etc). Thus 6 is the cost of the goat.

sheep(10) - dog(2) = 8 = goat (6) + dog (2)*** SPOILER ALERT! Click this link to display the potential spoiler text in this box. ***

");document.close();

 

[Peyton Marino]

Achmed and Ali are camel-drivers and on one day they decided to quit their job. They wanted to become shepherds. So they went to the market and sold all their camels. The amount of money(dinars) they received for each camel is the same as the total of camels they owned. For that money they bought as many sheep as possible at 10 dinars a sheep. For the money that was left they bought a goat.

On their way home they got in a fight and decided to split up. When they divided the sheep there was one sheep left. So Ali said to Achmed "I take the last sheep and you can get the goat". "That's not fair" said Achmed, "a goat costs lesser than a sheep". "Ok", Ali said "then I will give you one of my dogs and then we are even". And Achmed agreed.

What costs a dog?

mytagid = Math.floor( Math.random() * 100 );document.write("Pretty sure the dog costs 2 dinar

I'm pretty sure the only squares (#camels * cost of camels) with an odd whole multiple of 10 have a remainder of 6 (36, 196, 256, etc). Thus 6 is the cost of the goat.

sheep(10) - dog(2) = 8 = goat (6) + dog (2)*** SPOILER ALERT! Click this link to display the potential spoiler text in this box. ***

");document.close();

 

[Sweet J]

There are two lengths of rope.Each one can burn in exactly one hour.They are not necessarily of the same length or width as each other.They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.By burning the ropes, how do you measure exactly 45 minutes worth of time?

Off the top of my head:I'd light both ends of one rope (1/2 hour). When that is done, I'd cut the other rope in 1/2, then light both ends of each of the pieces (15 min)

Wow. Impressive.My answer was going to be to use a watch.

Cutting the second rope in half won't necessarily equal 15 minutes, though, because they aren't uniform width. The second rope may have one half burning faster than the other... lighting the halves could burn each half out in 10 and 20 minutes, for example.

He was really close. You don't need to cut it in half. You light both ends of rope 1 and one end of rope 2. When rope 1 burns out, you light the other end of rope 2. Regardless or non-uniformity in the thickness, it will burn out in exactly 45 minutes.

A agree that your answer is correct, but I still think I was right:We can all agree that lighting the first rope at both ends = 1/2 hour, correct?If so, why can't the same principles apply to the second rope? You cut the second rope in half, and you light all four ends (both ends of each 1/2 piece). The same principles apply to equal 1/4 hour (15 min.)

 

[Sweet J]

by the way, how do you do the :spoiler: tag?

 

[Dragons]

There are two lengths of rope.

Each one can burn in exactly one hour.

They are not necessarily of the same length or width as each other.

They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.

By burning the ropes, how do you measure exactly 45 minutes worth of time?

Off the top of my head:I'd light both ends of one rope (1/2 hour). When that is done, I'd cut the other rope in 1/2, then light both ends of each of the pieces (15 min)

Wow. Impressive.My answer was going to be to use a watch.

Cutting the second rope in half won't necessarily equal 15 minutes, though, because they aren't uniform width. The second rope may have one half burning faster than the other... lighting the halves could burn each half out in 10 and 20 minutes, for example.

He was really close. You don't need to cut it in half. You light both ends of rope 1 and one end of rope 2. When rope 1 burns out, you light the other end of rope 2. Regardless or non-uniformity in the thickness, it will burn out in exactly 45 minutes.

A agree that your answer is correct, but I still think I was right:We can all agree that lighting the first rope at both ends = 1/2 hour, correct?

If so, why can't the same principles apply to the second rope? You cut the second rope in half, and you light all four ends (both ends of each 1/2 piece). The same principles apply to equal 1/4 hour (15 min.)

mytagid = Math.floor( Math.random() * 100 );document.write("

What I normally do to find out how someone did something strange in a post is to reply to their post and see their tags.

[ spoiler ]

[ /spoiler]

*** SPOILER ALERT! Click this link to display the potential spoiler text in this box. ***");document.close();

 

[Nigel]

There are two lengths of rope.Each one can burn in exactly one hour.They are not necessarily of the same length or width as each other.They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.By burning the ropes, how do you measure exactly 45 minutes worth of time?

Off the top of my head:I'd light both ends of one rope (1/2 hour). When that is done, I'd cut the other rope in 1/2, then light both ends of each of the pieces (15 min)

Wow. Impressive.My answer was going to be to use a watch.

Cutting the second rope in half won't necessarily equal 15 minutes, though, because they aren't uniform width. The second rope may have one half burning faster than the other... lighting the halves could burn each half out in 10 and 20 minutes, for example.

He was really close. You don't need to cut it in half. You light both ends of rope 1 and one end of rope 2. When rope 1 burns out, you light the other end of rope 2. Regardless or non-uniformity in the thickness, it will burn out in exactly 45 minutes.

A agree that your answer is correct, but I still think I was right:We can all agree that lighting the first rope at both ends = 1/2 hour, correct?If so, why can't the same principles apply to the second rope? You cut the second rope in half, and you light all four ends (both ends of each 1/2 piece). The same principles apply to equal 1/4 hour (15 min.)

What if the two halfs are not uniform? One could burn twice as fast as the other.