A man crosses a road 250 metres wide in 75 seconds. His speed in km/hr is :

Answer: Option B

$$\begin{array}{rl}& S=\frac{D}{T}=\frac{250}{75}\text{ m/sec}\\ & \text{ = }\frac{250}{75}\times \frac{18}{5}\\ & =12\text{ km/hr}\end{array}$$