Question

how long would it take to walk around a circular Park whose diameter is 420 metre if its speed is 3 kilometre per hour

Answer 1

Time taken = 0.44hr = 28.4 minutes

Answer 2

Runner have to complete the circumference of circle.
circumference of circle=2πr
2×π×210/1000=1320/1000
speed=3km/h
By using D=S*T
1320/1000=3*T
T=440/1000=0.4h
hence he will completely it in 0.4h