Train A can cross a man in 8 sec and a 180 m long platform ‘P’ in 17 sec. If train A cross train B which is running in opposite direction at speed of 108 km/hr in 8 sec, then find time (in sec) taken by train B to cross platform P?

Train A crosses man in 8s, so length L = speed_A * 8. Crosses 180m platform in 17s, so L+180 = speed_A * 17. Solving: speed_A * 17 - 180 = speed_A * 8, so speed_A * 9 = 180, speed_A = 20 m/s. Length L = 160m. Train B speed = 108 km/hr = 30 m/s. Relative speed (opposite) = 20+30 = 50 m/s. Crossing time = (L+LB)/50 = 8, so LB = 240m. Train B crosses platform: (240+180)/30 = 420/30 = 14s. Answer D is correct.