A passenger train 150 m long is travelling with a speed of 36 km/hr. If a man is cycling in the direction of train at 9 km/hr, the time taken by the train to pass the man is :

Answer: Option D

Their relative speed in same direction :
= 36 - 9
= 27 km/hr
Time taken by train to cross the man = $$\frac{150}{27}$$
$$\left(\text{Time}=\frac{\text{Distance}}{\text{Speed}}\right)$$
$$\begin{array}{rl}& \text{Time}=\frac{150}{27\times \frac{5}{18}}\\ & \left[1\text{ km/hr}=\frac{5}{18}\text{m/s}\right]\\ & \text{Time = }\frac{150\times 18}{27\times 5}\\ & \text{Time = }\frac{30\times 2}{3}\\ & \therefore \text{ Time = 20 seconds}\end{array}$$