# Easy Time, Speed & Distance Solved QuestionAptitude Discussion

 Q. A man sitting in train travelling at the rate of 50 km/hr observes that it takes 9 sec for a goods train travelling in the opposite direction to pass him. If the goods train is 187.5m long. Find its speed
 ✖ A. 40 km/hr ✖ B. 30 km/hr ✖ C. 24 km/hr ✔ D. 25 km/hr

Solution:
Option(D) is correct

Let the speed of goods train be $x$ km/hr.

Then,

$(50+x)\times \dfrac{5}{18}=\dfrac{187.5}{9}$

⇒ x= 25 km/hr

Edit: For more insights into the solution check comment by Ketaki.

## (2) Comment(s)

Namrata Dash
()

Why the length of the train is not taken into consideration here?

Ketaki
()

Whenever we deal with such questions where there is a passenger sitting in a train and another train passes by, we dont add the length of that train to calculate the total distance in the formula i.e. Time = (length of train 1 + length of train 2)/ Relative Speed. In this case we would only take the length of 1 train (187.5m in this case) and time (9 sec) to derive at speed 25 km/hr.