A Brain Teaser Question

[CyberTiger]

One train leaves Los Angeles at 15 MPH heading for New
York. Another train leaves from New York at 20mph
heading for Los Angeles on the same track. If a bird,
flying at 25mph, leaves from Los Angeles at the same
time as the train and flies back and forth between the
two trains until they collide, how far will the bird
have traveled?

I don't have the answer. Do you?

 

[nateholtrop]

305 miles.


nate

 

Too far for a little birdie

 

[CyberTiger]

i believe you are just guessing.

 

[C1ue1ess]

What's the distance between LA & NY?

 

[Moonbeam]

The total distance times 1 and 2/5.

 

[syzygy]

what dumbass species of bird would engage in such pointless, non-survival
antics as you describe. what behavioral or biological prerogative do you give
for this bird to fly back and forth between two moving trains on certain
collision course with one another. perhaps its a passenger pigeon being
dispatched between two criminal masterminds to relay their secret messages ?
you think ! choke your professor for teasing your native gullibility.

 

[MiniThug]

nice answer syzygy

 

[tim0thy]

is this some sort of physics 101 question from college or high school?

 

[kranky]

Let's say the distance between NYC and LA is 2462 miles (Ask Jeeves said it was).

Trains are approaching each other at (15+20)= 35 mph. They will meet in 2462/35 = about 70 hours. In 70 hours the bird will fly 70*25 = 1750 miles.

Translating syzygy's post: "I have no idea".

 

[Cycad]

It will fly an infinite number of miles. If you say that the trains keep getting closer and closer then the bird goes back and forth. But if you keep taking the distance and cutting it in half then the trains will never collide, and the bird will go back and forth an infinite number of times and thus the distance is infinity.

 

[CyberTiger]

Moonbeam and Kranky got the right answer! You guys are smart.

Cycad: I was thinking along your line at first but the total distance traveled by bird is not infinite because the roundtrips are actually an infinte geometric sum. For example: 0.5 + 0.5/2 + 0.5/4 + 0.5/8 + .... = 1 (not infinity)

This was an interview question actually.

 

[kranky]

If by "smart" you mean "good with search engines", then I thank you.