Train A leaves Ludhiana for Delhi at 11 am, running at the speed of 60 km/hr. Train B leaves Ludhiana for Delhi by the same route at 2 pm on the same day, running at the speed of 72 km/hr. At what time will the two trains meet each other ?

Answer: Option B

Distance covered by train A from 11 am to 2 pm i.e., in 3 hours :
= (60 × 3) km
= 180 km
Relative speed :
= (72 - 60) km/hr
= 12 km/hr
Time taken to cover 180 km at relative speed :
= $$\frac{180}{12}$$ hrs
= 15 hrs
So, the two trains will meet 15 hrs after 2 pm i.e., at 5 am on the next day.