# Distance between two stations is 400km. Two trains start simultaneously from these stations...

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The distance between two stations is 400km. Two trains start simultaneously from these stations on parallel tracks to cross each other. The speed of one of them is greater than the other by 5 km/hr. If the distance between the two trains after two hours of their start is 170 km, find the speed of each train?

posted Sep 30, 2018

Speed of Train 1 = S1
Speed of Train 2 = S2 = S1 + 5
This problem can be simplified if we add the speed of train 1 to train 2 (because the relative velocities add up). This makes the train 1 stationary at the first station.
After 2 hours the distance between the trains = 170Km
The distance travelled by train 2 in 2 Hrs = 400 - 170 = 230Km
Therefore speed of Train 2 = S1 + S1 + 5 = 2S1 + 5 = 230/2
S1 = 55Km/hr & S2 = 60Km/hr.

55 km/hr & 60 km/hr

Tr1 speed = x km/hr
Tr2 speed =x+5 km/hr
(x+x+5)*2=400-170 => 4x=220 => x=55 km/hr, y=60 km/hr

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