Two methods for such problems

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Two methods for such problems

by towerSpider » Tue Jan 04, 2011 2:54 am
Train b is 40 m ahead of train a. Train a is travelling at 60m/h and train b at 50m/h. How long would it take train a to catch train b?

Method one: since the coverage speed is 10m/h and distance to cover is 40m : s=d/t
10=40/t
T=4hrs
Method two:
Only two things which would be equal when both are together would be time so we set up equation:

A. . .. .b
D/s=d/s (since t=d/s)
X/60=(X-40)/50 (let X be distance covered by train a)
50X=60X-2400
X=240 (this is distance that must be covered by train a)
Time taken by train a:
240/60=4 hrs
Source: — Problem Solving |

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by Target2009 » Fri Jan 07, 2011 9:03 pm
Resolutoin . Time = Distance / Relative speed = 40 / ( 60-50) = 4 hrs

Relative Speed in case Both running in
same direction = Speed 1 - speed 2
opposite direction = Speed 1 + speed 2