Rakesh P.

asked • 07/30/17

how can we solve this ques without forming linear equations or in the shortest way possible.

 a train overtakes two persons walking @ 4.5 km/hr and 5.4km/hr. the train takes 8.4 and 8.5 seconds respectively to overtake them. what is the speed of the train if they are walking in the same direction as that of train??  

1 Expert Answer


Andy C. answered • 07/30/17

4.9 (27)

Math/Physics Tutor

Rakesh P.



Rakesh P.

but you have done it wrong. the train will have some length of its own. that also needs to be added in the ttal distance travelled by tarin


Andy C.

Yes, but it gets cancelled out by the distance that the two people walked.
Moreover, we know NONE of these distances walked by the people or traveled by the train.
The only thing we have is the 2.1 meters between the two pedestrians and the 0.1 seconds
of time the train takes to pass them both. That is all that is needed to find the speed of the train.
Try to model the problem like this
where Xr marks the spot of the pedestrians as the train passes by.
In that short time-span of 0.1 second, the train travels 2.1 meters.
Distance = rate x time.
DIstance = 2.1 meters
Time = 0.1 seconds.
That's all we need to find the speed of the train.
What happens before that is irrelevant.


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