Question

How long will a man take to make a round of a circular field of radii 21cm, cycling at the speed of 8km/h?

Answer 1

Check this attachment :-)

Answer 2

total distance of the man will be equal to circumference of circle
circumference of circle =2πr
=2×22/7×21
=2×22×3
44×3
=132m

speed =8km/h
8×5/18
=2.22m/s
time=distance/speed
132/2.22
59.4s