The distance between two stations A and B is 420 km. A train starts from A at 3 p.m. and travels towards B at a speed of 60 km/h. Another train starts from B at 4 p.m. and travels towards A at a speed of 30 km/h. At what time do they meet?

Correct option is D

Given:

Distance between A and B = 420 km

Speed of Train 1 (from A) = 60 km/h

Speed of Train 2 (from B) = 30 km/h

Train 1 starts at 3 p.m.

Train 2 starts at 4 p.m.

Formula Used:
Distance = Speed × Time

Solution:
Train 1 travels for 1 hour before Train 2 starts, so it covers:
60 km/h × 1 h = 60 km

Remaining distance = 420 km – 60 km = 360 km

Relative speed = 60 km/h + 30 km/h = 90 km/h

Time taken to meet after 4 p.m. = $$\frac{360}{ 90 }$$​ = 4 hours

Meeting time = 4 p.m. + 4 hours = 8:00 p.m.