A person sprints around a circular track and stops after running 40 percent around the circumference of the track. If the total distance traveled was 80π meters, what is the diameter of the circular track?
if 40% is 80 pi, then 100% (or the whole lap) is 80pi*100/40=200pi; because the circumference is pi * diameter, the diameter is 200pi/pi=200 meters
