A train P leaves Mumbai at 6:00 am and reaches Nagpur at 9:00 am. Another train leaves Nagpur at 7:00 am and reaches Mumbai at 9:00 am. At what time both the trains cross each other?

Correct option is C

Given:
Time taken by train to reach Nagpur from Mumbai = 3 h
Time taken by another train to reach Mumbai from Nagpur = 2 h
Formula used:
Time = Distance/Speed
Concept Used:
Relative Speed = Speed of one object with respect to other object
If two object of Speed V1 and V2, respectively travels in opposite direction, Relative Speed = |V1 + V2|
Solution:
Let Total distance between Nagpur and Mumbai be x km
Speed of first train = (x/3) km/h
Speed of second train = (x/2) km/h
First train left 1 h earlier, so distance travelled in 3 h = x/3 × 1 = x/3 km
Now, Distance between the trains = x – x/3 = 2x/3
Relative speed = x/3 + x/2 = 5x/6 km/h
Time taken to meet = (2x/3)/(5x/6) = (4/5) in hour
In min, (4/5)× 60 = 48 min
∴ Trains will meet at 7:48 am.