RRB NTPC Mains or Stage 2 Model Paper 6 with solutions

(c) When 2nd train starts i.e. at 7 AM (1 hr after 6 AM), distance covered by first train is 60 km (i.e. in 1 hr).
Now 2nd train also starts and distance between them is now (480-60) = 420 km Both coming in opposite direction, so relative speed = (60+80) = 140 km/hr So time = 7:00 AM + (420/140) = 7:00 AM+3 hrs = 10:00 AM