25 replies to this topic

[PMitra]

The easy way is to calculate the time when both the trains crashes which is 200/100=2hours (100km/h is the respective speed of the trains) now simply multiply the speed of fly to get distance traveled which is 75*2=150 km (Does this gives result........ )

[SPENGLER]

this shouldn't be hard. i'll post my theory and then check the spoiler.

1. trains == 200 kms apart
2. trains == 50 kms / hour, and will collide @ the 100km mark (in the middle)
3. fly == 75 kms / hour, oscillates between the trains until the trains travel 100 kms
4. fly == is going 50% faster than trains, fly must have gone 150kms total.

[SPENGLER]

I'd like to point out that there is a minor detail which has not been considered. Assuming that the fly begins his suicidal flight at the precise time that the trains are at their original points, then the calculation presented would be correct. However, the puzzle, as stated, does not in fact say when the fly begins his spiraling death. If he were to start flying half way through the trip for example, then he would only travel 75km. Therefore, unless the puzzle is reworded, the answer would rely on the point in which the fly has his nervous break down and decides that existence is futile.

fast fly, and ...

oes it take off from the engine of the train or the caboos?
how long is the train that it leaves from?

i seen a lot of posts with questions like this today and i'm not sure if it's people over thinking the problem, or just trying to appear more intelligent that they are by asking questions that can be inferred. if the length of the train is not mentioned ... IT DOESN'T MATTER.

[Dreaken667]

You misunderstand. I agree with the answer given. My only point is that the answer given does rely on assumptions.

[mgtfernandez]

the 2 trains will collide after 2 hrs, since both are travelling at a rate of 50kph... the distance they will travel will be 100kms. this will also be the same time the fly will travel. applying the formula distance travelled = speed multiplied by time, 75 km/hr x 2hrs, will gie a result of 150km...

[credels]

Yes, but everyone knows that flys only live for 2 weeks-max! The fly could have been half dead when it was initially involved in the whole affair!

[Bball3]

Well I get most of your puzzles but i have to say i didnt get that one o well

[Quinten27]

fast fly, and ...

oes it take off from the engine of the train or the caboos?
how long is the train that it leaves from?

i seen a lot of posts with questions like this today and i'm not sure if it's people over thinking the problem, or just trying to appear more intelligent that they are by asking questions that can be inferred. if the length of the train is not mentioned ... IT DOESN'T MATTER.

Well, the question doesn't state that the trains are on the same track, so can we be SURE that they will even collide? Maybe the trains pass right by each other and the fly is free to keep flying between them as long as he can fly? Which makes for another interesting brain teaser/math problem...........would the fly be able to touch each train 3 times in 1 hour, after the trains pass each other????? Assume that the trains are still moving 50 kph and the fly is going 75 kph.

[JoyfullyOrange]

I'd like to point out that there is a minor detail which has not been considered. Assuming that the fly begins his suicidal flight at the precise time that the trains are at their original points, then the calculation presented would be correct. However, the puzzle, as stated, does not in fact say when the fly begins his spiraling death. If he were to start flying half way through the trip for example, then he would only travel 75km. Therefore, unless the puzzle is reworded, the answer would rely on the point in which the fly has his nervous break down and decides that existence is futile.

I know these puzzles are old, but I just started getting them on my iGoogle page and this one just came up. My original question before trying to answer was when the fly took off from the first train. I give Kudos to Dreaken667 because of the terminology used of the fly beginning his suicidal flight ... bc of his nervous break down and deciding his existence is futile. We humans have a tendency to wish we were a fly on the wall of someone when something specific happens; but to try to imagine why a fly would make a suicide flight is just too much. So, it would have to be assumed in human logic that the fly had a nervous breakdown and felt his life could make no difference so why not fly to its death and have someone make a puzzle out of it! I thought it was worth a laugh:D

[wbrode]

I think this is a solid puzzle, if you want to make it a little more technically correct, it should say that the fly is flying at 75kph relative to ground. I only say this because as soon as i saw the words "the fly takes off from the train" I thought he was flying at 50kph from being on the train and you add that to the 75 (if it was relative to the train) for a total velocity of 125kph relative to ground. Its really probably not an issue for anyone other than me and most people would assume it, but it is more technical.