A train is running at the speed of 80 km/hr from A to B at 7 am. At the same time another train is running from B to A at the speed of 40 km/hr. If they are running on parallel tracks and the distance between two stations is 480 km, then at what time will they start to cross each other?

11:00 am

Distance b/w two station = 480 km

Relative speed in opposite direction = 80 + 40 = 120 km/hr

Time = \(\frac{distance}{relative\;speed}\) = \(\frac{480}{120}\) = 4 hours

Train will start to cross each other at = 7:00 am + 4 hours = 11:00 am