Question

how do I figure the circumference of race track that takes 3 lap to make a mile?

Answer 1

I think we must assume the race track is a circle.
Let's work in feet,
there are 5280 feet in a mile, since it takes 3 laps to make a mile
each lap is 5280/3 or 1760 ft for one lap.

So the circumference of the race track is 1760 feet.