During the time that a car travels 4 miles, its tires make 3000 revolutions. What is the radius of the tires in inches?

Answer 1

1 revolution of the tire advances the vehicle 2*pi*r ft where pi = 3.14159, & r = radius of the tire (ft)

So, 1 revolution = 2*pi*r ft multiply by 3000, then

3000 revolutions = 2*(3000)*pi*r but then 6000*pi*r = 4 miles = 21,120 ft

Solving for r = 1.12 ft = 13.45 inches