Question

Two Station X and Y are 820 km apart from each - other. One train A starts from station X with speed of 60 kmph. After two hours another train B started from station Y with speed of 40 kmph. Find the time after which they will meet each -other after train A began its journey?

1. 5 hour
2. 9 hour
3. 8 hour
4. 6 hour

Answer 1

Correct Answer - Option 2 : 9 hour

Given - 

distance between two station = 820 km

speed of train A = 60 kmph

speed of train B = 40 kmph

Concept used - 

when two trains started moving in opposite direction,

relative speed = (sum of their speed)

Formula used - 

speed = distance/time

Solution - 

Let the both train meets after t hour.

⇒ Train A started from station X

⇒ distance travelled by train A in 2 hour = 60 × 2 = 120 km

⇒ remaining distance = (820 - 120) km = 700 km

⇒ Both the trains moving towards each - other

⇒ relative speed = (60 + 40) kmph = 100 kmph

⇒ time = (700/100) = 7 hr.

⇒ After (7 + 2) hr = 9 hr they meet each - other.

∴ Afer 9 hr both the trains meet each - other.