The distance between two stations ‘P’ and ‘Q’ is 138 km. A train starts from ‘P’ towards ‘Q’ and another from ‘Q’ to ‘P’ at the same time a… — Answer & Discussion

The distance between two stations ‘P’ and ‘Q’ is 138 km. A train starts from ‘P’ towards ‘Q’ and another from ‘Q’ to ‘P’ at the same time and they meet after 6 hours. The train travelling from ‘P’ to ‘Q’ is slower by 7 km/h compared to other train from ‘Q’ to ‘P’. What is the speed of the slower train?

A16 km/h
B12 km/h
C8 km/h
D24 km/h

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Discussion 1

CCommunity14 Jun 2019

Let the speed of the slower train be ‘x’ km/h, then,

Speed of the faster train = ‘x + 7’ km/h.

The trains are moving in opposite directions, so the relative speed = x + (x + 7) km/h

And, time taken = Distance/Speed

$(\Rightarrow 6 = \frac{{138}}{{2x + 7}})$

⇒ 2x + 7 = 138/6

⇒ 2x + 7 = 23

⇒ x = 16/2 = 8 km/h

∴ Speed of the slower train = 8 km/h.