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Bird Flying between Trains


Date: 08/30/97 at 21:57:58
From: Koury
Subject: Word problem

Two trains are 150 kilometers apart and are heading toward each other 
along a single track. The first train is going 90 kilometers an hour; 
the second train is going 60 kilometers an hour. Flying at a constant 
speed of 110 kilometers an hour, a bird takes off from the head of the 
first train, flies to the head of the second, immediately turns and 
flies back to the head of the second, and keeps going like this until 
the two trains crash.

How far does the bird fly?

Koury


Date: 08/31/97 at 08:45:55
From: Doctor Anthony
Subject: Re: Word problem

This sort of problem is best done using a little lateral thinking.  

Since the trains start 150 km apart and have a closing speed of 
90+60 = 150 km/hr, they will meet in exactly 1 hour.  

The bird is flying at a speed of 110 km/hr, so in 1 hour it flies 110 
km.

Distance flown by bird =  110 km.

-Doctor Anthony,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/   
    
Associated Topics:
Middle School Word Problems

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