[ricktendo]

Jump in the water, take my chance with the sharks (have dove with sharks before, there cool, only interested in fish)

[Tripredacus]

I posed this question to someone else, he said "make a boat out of the trees" and I told him he had no tools. He said "Tom Hanks didn't have tools in Cast Away". I thought Robinson Crusoe was a better idea.

[5eraph]

Given the following new information I have another solution that may be more plausible:

gamehead200, on 09 April 2010 - 05:39 AM, said:

The treetops are low enough to the ground that if you were to approach a tree that was on fire, it is likely that you would catch fire. The lightning bolt strikes a tree while its raining. [It's not raining hard enough to extinguish or prevent the spread of the fire.]

[Sharks do not fear tree branches.]

Let's not think of about long-term survival

In this solution let us assume that I'm human in the real world. Further, it is known that trees cannot grow in concrete and that the trees are short as stated above. Therefore, all trees on our concrete island are potted and low enough in mass to be tipped.

The trees are dense enough to prevent a person from walking between them without coming into contact with them. However, since they're densely clustered, I will tip a nearby tree into any burning tree and cause a cascade of falling trees that will clear a path for me to an area of the island that is no longer on fire. Or, to save some trees, I simply tip trees in a line to block the spread of the fire.

I have survived the fire without tempting the sharks until my inevitable rescue by flying eagles.

This post has been edited by 5eraph: 09 April 2010 - 02:36 PM

[gamehead200]

GrofLuigi, on 09 April 2010 - 06:55 AM, said:

Again depending on more variables: shape of the island, wind, rate at which the fire spreads, 'geometry' by which it spreads (radial/perfect circle?)...

I break one branch off, set it on fire and start another fire at the opposite end of the island (not directly oposite - imagine a triangle within a circle - touching point 1 is the thunder fire, 2 is the fire I started, and 3 is where I run to). The two fires should cancel out (burn each other's fuel).

There is a tiny flaw though - at some point I'll need to cross the 'line of fire'.

I'm dead, I know...

GL

Believe it or not, your answer is pretty close to the actual answer I was told. But think a bit harder... What would happen if you were to set two fires, both spreading in the same direction and burning at the same rate (ignore geometry for now)?

5eraph, on 09 April 2010 - 01:57 PM, said:

Given the following new information I have another solution that may be more plausible:

gamehead200, on 09 April 2010 - 05:39 AM, said:

The treetops are low enough to the ground that if you were to approach a tree that was on fire, it is likely that you would catch fire. The lightning bolt strikes a tree while its raining. [It's not raining hard enough to extinguish or prevent the spread of the fire.]

[Sharks do not fear tree branches.]

Let's not think of about long-term survival

In this solution let us assume that I'm human in the real world. Further, it is known that trees cannot grow in concrete and that the trees are short as stated above. Therefore, all trees on our concrete island are potted and low enough in mass to be tipped.

The trees are dense enough to prevent a person from walking between them without coming into contact with them. However, since they're densely clustered, I will tip a nearby tree into any burning tree and cause a cascade of falling trees that will clear a path for me to an area of the island that is no longer on fire. Or, to save some trees, I simply tip trees in a line to block the spread of the fire.

I have survived the fire without tempting the sharks until my inevitable rescue by flying eagles.

Good work at the assumptions - if I were the interviewer, I'd accept this as a valid answer.

[GrofLuigi]

gamehead200, on 09 April 2010 - 04:13 PM, said:

GrofLuigi, on 09 April 2010 - 06:55 AM, said:

Again depending on more variables: shape of the island, wind, rate at which the fire spreads, 'geometry' by which it spreads (radial/perfect circle?)...

I break one branch off, set it on fire and start another fire at the opposite end of the island (not directly oposite - imagine a triangle within a circle - touching point 1 is the thunder fire, 2 is the fire I started, and 3 is where I run to). The two fires should cancel out (burn each other's fuel).

There is a tiny flaw though - at some point I'll need to cross the 'line of fire'.

I'm dead, I know...

GL

Believe it or not, your answer is pretty close to the actual answer I was told. But think a bit harder... What would happen if you were to set two fires, both spreading in the same direction and burning at the same rate (ignore geometry for now)?

It crossed my mind (square within a circle; or other polygons). But no matter how many fires I start, I will always have to retreat to an area with trees - and I can't imagine a situation where it won't spread towards me. If I start a fire in the middle, the two fires will cancel each other out on the other side, but 'my' fire will go towards me.

It's all about geometry

GL

[5eraph]

GrofLuigi is correct. Fire only ever travels in one direction: outward from the starting point. In the absence of natural restrictions in the terrain, it will spread in an expanding circular pattern. Refuge must be created before starting a new fire because fire knows no ally.

This post has been edited by 5eraph: 10 April 2010 - 02:20 AM

[submix8c]

?WTH? Am I missing something?

Standard practice is a Firebreak... Go to the middle, set another fire, follow the burn and let the original fire burn its course to previously (you) burned area. Even if it moves outward (toward you again), you can still walk around the outer unburned area back into the (your) burned area.

SOP (or is this some kind of trick question)

(edit - same answer as last two I just noticed... a little obvious)

This post has been edited by submix8c: 10 April 2010 - 09:50 AM

[gamehead200]

GrofLuigi, on 10 April 2010 - 12:05 AM, said:

gamehead200, on 09 April 2010 - 04:13 PM, said:

GrofLuigi, on 09 April 2010 - 06:55 AM, said:

Again depending on more variables: shape of the island, wind, rate at which the fire spreads, 'geometry' by which it spreads (radial/perfect circle?)...

I break one branch off, set it on fire and start another fire at the opposite end of the island (not directly oposite - imagine a triangle within a circle - touching point 1 is the thunder fire, 2 is the fire I started, and 3 is where I run to). The two fires should cancel out (burn each other's fuel).

There is a tiny flaw though - at some point I'll need to cross the 'line of fire'.

I'm dead, I know...

GL

Believe it or not, your answer is pretty close to the actual answer I was told. But think a bit harder... What would happen if you were to set two fires, both spreading in the same direction and burning at the same rate (ignore geometry for now)?

It crossed my mind (square within a circle; or other polygons). But no matter how many fires I start, I will always have to retreat to an area with trees - and I can't imagine a situation where it won't spread towards me. If I start a fire in the middle, the two fires will cancel each other out on the other side, but 'my' fire will go towards me.

It's all about geometry

GL

5eraph, on 10 April 2010 - 02:11 AM, said:

GrofLuigi is correct. Fire only ever travels in one direction: outward from the starting point. In the absence of natural restrictions in the terrain, it will spread in an expanding circular pattern. Refuge must be created before starting a new fire because fire knows no ally.

submix8c, on 10 April 2010 - 09:48 AM, said:

?WTH? Am I missing something?

Standard practice is a Firebreak... Go to the middle, set another fire, follow the burn and let the original fire burn its course to previously (you) burned area. Even if it moves outward (toward you again), you can still walk around the outer unburned area back into the (your) burned area.

SOP (or is this some kind of trick question)

(edit - same answer as last two I just noticed... a little obvious)

submix8c explained it the best.

[bphlpt]

I guess that GrofLuigi and 5eraph were thinking as I was about fire traveling similar to ripples from rocks thrown in a pond - outward from the center in a circle. If that were true a firebreak wouldn't work, since as GrofLuigi stated:

"I can't imagine a situation where it won't spread towards me. If I start a fire in the middle, the two fires will cancel each other out on the other side, but 'my' fire will go towards me."

But that doesn't take into account wind, which will always drive a fire away from it faster than in can come toward it, so on the (assuming) flat concrete island it will go in mostly one direction, or at least in a spreading cone shape. And if there were absolutely no wind, it would indeed expand in a circle, but it would create wind blowing toward it from the updraft caused by the heat from the fire. You could then use that wind and create small fires at the edge of the expanding circle, where the greater heat from the larger fire would pull the other fires toward it creating a safe zone for you. Do I have the theory correct?

Cheers and Regards

[MrJinje]

You can't treat a wild-fire like a camp fire, that is rubbish, large fires radiate heat much farther than a tiny camp fire. Fact is that you would start cooking before you ever got your stick lit, so setting a fire-break will not work unless you have another way of starting it.

Quote

A wildfire front is the portion sustaining continuous flaming combustion, where unburned material meets active flames, or the smoldering transition between unburned and burned material. As the front approaches, the fire heats both the surrounding air and woody material through convection and thermal radiation. First, wood is dried as water is vaporized at a temperature of 100 °C (212 °F). Next, the pyrolysis of wood at 230 °C (450 °F) releases flammable gases. Finally, wood can smolder at 380 °C (720 °F) or, when heated sufficiently, ignite at 590 °C (1,000 °F). Even before the flames of a wildfire arrive at a particular location, heat transfer from the wildfire front warms the air to 800 °C (1,470 °F), which pre-heats and dries flammable materials, causing materials to ignite faster and allowing the fire to spread faster. High-temperature and long-duration surface wildfires may encourage flashover or torching: the drying of tree canopies and their subsequent ignition from below.

This post has been edited by MrJinje: 10 April 2010 - 01:58 PM

[Redhatcc]

Here is my idea lol...


If it is a school of sharks, they are in a group, swimming around the island as one single unit? You would get in the water when they are on the opposite side of the island, and swim in the same direction as the sharks at the same speed, you will never catch them and they will never catch you. Then wait until the fire is burnt out.

And if this matters, make a boat out of unburnt wood, then do the steps above.

Close?

[ricktendo]

I answer him with a question

Why is the island made entirely of concrete?

[gamehead200]

bphlpt, on 10 April 2010 - 01:04 PM, said:

I guess that GrofLuigi and 5eraph were thinking as I was about fire traveling similar to ripples from rocks thrown in a pond - outward from the center in a circle. If that were true a firebreak wouldn't work, since as GrofLuigi stated:

"I can't imagine a situation where it won't spread towards me. If I start a fire in the middle, the two fires will cancel each other out on the other side, but 'my' fire will go towards me."

But that doesn't take into account wind, which will always drive a fire away from it faster than in can come toward it, so on the (assuming) flat concrete island it will go in mostly one direction, or at least in a spreading cone shape. And if there were absolutely no wind, it would indeed expand in a circle, but it would create wind blowing toward it from the updraft caused by the heat from the fire. You could then use that wind and create small fires at the edge of the expanding circle, where the greater heat from the larger fire would pull the other fires toward it creating a safe zone for you. Do I have the theory correct?

Cheers and Regards

Yeah, the wind is key here... I guess that's something else I forgot to mention in the original situation. Oops...

Redhatcc, on 10 April 2010 - 01:53 PM, said:

Here is my idea lol...


If it is a school of sharks, they are in a group, swimming around the island as one single unit? You would get in the water when they are on the opposite side of the island, and swim in the same direction as the sharks at the same speed, you will never catch them and they will never catch you. Then wait until the fire is burnt out.

And if this matters, make a boat out of unburnt wood, then do the steps above.

Close?

Let me ask you this... How fast can you swim? Definitely not as fast as a shark, I would think...

[5eraph]

bphlpt, on 10 April 2010 - 01:04 PM, said:

I guess that GrofLuigi and 5eraph were thinking as I was about fire traveling similar to ripples from rocks thrown in a pond - outward from the center in a circle. If that were true a firebreak wouldn't work

That was my thinking as illustrated in the crude image below.

 05 - Fires Merged.png (22.34K)
Number of downloads: 9

I am the blue dot, my fire started at the yellow dot, and the lightning struck at the yellow lightning bolt. The black area is burned but safe. The green area is unburned. And the red outline on the burned area indicates the fire line that cannot be crossed or touched. As is evident in my image, I'm screwed with less time than I originally had if I hadn't started another fire.

bphlpt, on 10 April 2010 - 01:04 PM, said:

But that doesn't take into account wind, which will always drive a fire away from it faster than in can come toward it, so on the (assuming) flat concrete island it will go in mostly one direction, or at least in a spreading cone shape. And if there were absolutely no wind, it would indeed expand in a circle, but it would create wind blowing toward it from the updraft caused by the heat from the fire. You could then use that wind and create small fires at the edge of the expanding circle, where the greater heat from the larger fire would pull the other fires toward it creating a safe zone for you.

Assuming that is correct, you cannot expect a layperson to know that information. If I were interviewing for a firefighter's position then this would be a fair question. It's not a fair question to ask of somebody you pulled off the street.

gamehead200, on 10 April 2010 - 02:08 PM, said:

Yeah, the wind is key here... I guess that's something else I forgot to mention in the original situation. Oops...

I would not have arrived at the desired answer even if you had mentioned the wind. Specific knowledge was tested, not common sense as it should have been.

Good questions an interviewer should ask should either be directed toward information the prospective employee should already know, or general logic questions that rely on common knowledge that will reveal to the interviewer how the prospective employee thinks and arrives at conclusions. As I said above, this would be a good question to ask of a firefighter, not a network technician or car mechanic.

This post has been edited by 5eraph: 10 April 2010 - 03:08 PM

[cluberti]

5eraph, on 10 April 2010 - 02:22 PM, said:

Assuming that is correct, you cannot expect a layperson to know that information. If I were interviewing for a firefighter's position then this would be a fair question. It's not a fair question to ask of somebody you pulled off the street.

You miss the point of questions like this - it's not to get the correct answer, it's so the interviewer can "see" how the interviewee thinks, and what kind of mental horsepower he or she has. You get asked logic questions with less-than-obvious answers (and ridiculous situations) partially because they would never happen in real life, so you have to really think hard about your answers. You miss the point of the questions entirely.

5eraph, on 10 April 2010 - 02:22 PM, said:

Good questions an interviewer should ask should either be directed toward information the prospective employee should already know, or general logic questions that rely on common knowledge that will reveal to the interviewer how the prospective employee thinks and arrives at conclusions. As I said above, this would be a good question to ask of a firefighter, not a network technician or car mechanic.

Asking someone things they already know will only tell you certain things about a person. If you want to find out also how well they react to odd situations, or how someone thinks on their feet, asking questions you would reasonably expect an interviewee to know gets you nothing. Again, you miss the point of asking these types of questions in the first place - it's fairly common in a dev interview to get dev questions, logic questions, and interpersonal-type questions. Assuming you're a decent dev, and not a complete jerk, the only part that will be "hard" will be the logic questions, and it's something that can get you a job or lose you a job, honestly, as most other interviewees who make it past the first screening are also likely decent at their job (at least), and are problably decent people as well.

[5eraph]

But I do understand all that, cluberti. gamehead200 was looking for a specific answer involving wind. Please read my previous response more carefully if you don't believe me.

gamehead200, on 08 April 2010 - 05:35 PM, said:

[...] this isn't the answer.

gamehead200, on 10 April 2010 - 02:08 PM, said:

the wind is key here...

This post has been edited by 5eraph: 22 April 2010 - 09:47 AM

[JustShootIt]

gamehead200, on 07 April 2010 - 11:46 AM, said:

I got asked this in an interview once so that the interviewer could understand my thought process. The answer is actually extremely simple, but unfortunately, I wasn't able to get the right answer at the time.

Here goes...

You're stranded on an island made entirely of solid concrete (comment: unlikely, but OK) in the middle of the ocean. The island has nothing but trees on it. There is a school of sharks swimming around the island. While you're on one side of the island, a lightning bolt strikes a tree on the opposite side of the island and the tree catches fire. Slowly, but surely, the fire spreads from one tree to the next and makes its way towards you.

How do you survive?

I think that if an employer made a decision on such a ridiculous basis, I would go looney if I worked there. A pefect example of "business school thought"...someone who doesn't even know the job their employees do, while trying to tell them how to do it, because they don't have the brains to do even the simplest job themselves. Save me from that type!

[puntoMX]

JustShootIt, on 17 May 2010 - 05:22 PM, said:

Save me from that type!

Any way, a silly question will have a silly answer I would say (flame me! ), sooo: I will turn into a beaver and use my teeth to get that tree down, heck, I would not live long on some concrete with burned trees, I would take my last swim or stick my head out towards a shark to make it quick!