Distance runners often run around an approximately circular trajectory. However, since some runners are running at a larger radius than others, they must be given an advantage in the beginning so that the race is fair.

If the path of the runner running at a greatest radius of 20 m is 100 m long, how far behind in m should the runner at the smallest radius start? The smallest radius is 15 m.

3 answers

distance will be proportional to radius.

(perimeterofCircle=PI*2*radius)

difference in perimeters=2PI*(20-15)

so that distance is the how far behind should the inner radius be.
So, what is the answer?
I am not sure how you are calculating this problem since you wrote it in abbreviations so could you please explain again?