2 trains in same direction at 50km/hr,32 km/hr.A man in slower train observes 15 sec elapse before the faster train completely passed by him what is length of faster train?  Select
A) 65 meters B) 75 meters C) 85 meters D) 95 meters E) 55 meters

Rationale: relative speed = 18 k / hr = 5 m / sec distance covered = length of faster train = 5 * 15 = 75 meters answer : b
Answer: B