Question

Mohan is driving a car. He takes 12 minutes to cross a bridge while travelling uniformly at a speed of 40km/hr. How long is the bridge?

• A. 8 km
• B. 10 km
• C. 12 km
• D. None of these

Answer 1

The correct option is A

8 km

Time taken to cross the bridge = 12 minutes

60 minutes = 1 hour

1 minute = $\frac{1}{60}$ hr

12 min = 12 $\times$ $\frac{1}{60}=\frac{12}{60}$ hrs = $\frac{1}{5}$ hrs

Therefore, the time taken to cross the bridge = 12 minutes = $\frac{1}{5}$ hrs

Speed of the car = 40 km/hr

Distance = Speed $\times$ Time = 40 $\times$ $\frac{1}{5}$= $\frac{40}{5}$=8 km