A person crosses a 500 m long street in 5 minutes. What is his speed in km/h?

Distance = 500 m = 0.5 km (since 1 km = 1000 m)

Time = 5 minutes = 5/60 = 1/12 hours (since 1 hour = 60 minutes)

Speed = Distance / Time = 0.5 km / (1/12) hours = 0.5 km × 12/1 = 6 km/h

So, the correct answer is: 6