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 :

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