How many seconds will a 900 metre long train take to cross a man walking with a speed of 3 km/hr in the direction of the moving train if the speed of the train is 63 km/hr? Choose the most appropriate option.
A) 25
B) 30
C) 40
D) 45
E) 54

Rationale: "relative speed of the train = 63 - 3 = 60 kmph = 60 * 5 / 18 = 50 / 3 m / sec t = 900 * 3 / 50 = 54 sec answer : e"
Answer: E