A person crosses a 700 m long bridge in \(3\displaystyle\frac{1}{2}\) minutes. The speed of the person in km/h is
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 12
Speed = distance ÷ time; for km/h, change the distance to kilometres and the time to hours first.
Distance \(=700\) m \(=0.7\) km
Time \(\displaystyle=3\frac{1}{2}\text{ min}=\frac{3.5}{60}\text{ h}\)
Speed \(\displaystyle=0.7\times\frac{60}{3.5}=\) 12 km/h