Question

What must be the radius of a circular running path, around which an athlete must run 5 times in order to describe 1 km?

Answer 1

Distance travelled in 5 rounds = 1 km = 1000 m 

Distance travelled in 1 round = 1000/5 = 200 m

Let the radius of the circular path be r metre

So 2πr = 200 

(i.e) 2 x (22/7) x r = 200

∴ r = (200 x 7)/44 = 31.82 cm