Correct Answer - Option 3 : 11 : 00 am
Calculation:
Distance traveled by train from A from 9:00 am to 10:30 am = 1:30 hours × 40 km/hr = 60 km
Remaining distance to travel = 90 - 60 = 30 km
Time when both trains meet = 30/(40 + 20) = 1/2 hour from 10:30 am
∴ At 11:00 am both trains will meet each other.
The relative speed of two trains = speed of the train from A + Speed of train from B
(As they are moving towards each other)
Time = distance/(Speed A + Speed B)