Given: Two trains start from a certain place on two parallel tracks in the same direction. The speed of the trains are 45 Km/hr and 40 Km/hr respectively. Formula Used: Distance = speed × time Calculation: Relative speed of 1st train with respect to second train = 45 – 40 = 5 km/hr Distance between them in 48 min = 5 × 48/60 = 4 km