Question

Two trains started at 7 AM from the same point. The first train travelled north at a speed of 80 km/h and the second train travelled south at a speed of 100 km/h. The time at which they were 540 km apart is ______ AM.
1. 9
2. 10
3. 11
4. 11.30

Answer 1

Correct Answer - Option 2 : 10

Concept:

\(Time=\frac{Distance}{Relative\;Speed}\)

Calculation:

Given:

Starting Time = 7 AM, Distance = 540 km.

Speed of the first train = 80 km/h, Speed of the second train = 100 km/h.

As they are moving in two opposite direction, their relative speed will get added.

Relative speed = (80 + 100) = 180 km/hr

\(Time=\frac{Distance}{Relative\;Speed}\)

\(Time=\frac{540}{180}=3\;hr\)

After 3 hr i.e. at 10 AM they will be at a distance of 540 km from each other.