A car travels 10 miles. Its tires make 8800 revolutions. What is the radius of a tire in inches?

Question

 precal, answer must be in inches

 

Answer 1

10 miles = 10(5280)(12) inches = 633,600 inches

 

633,600 inches = (8800)(2πr) ⇒

 

r = (633,600) / [(8800)(2π)] inches ≅ 11.46 inches

Answer 2

                    5280 feet    12 inches

10 miles x -------------- x ---------- = 633600 inches

                  1 mile           1 ft

 

633600 / 8800 = 72 inches per revolution

 

So the perimeter (or circumference) of the tire is 72 inches.

 

The pi * diameter = 72

 

      22/7 * D = 72

 

      D = 72*7/22 = 22.90

 

The radius is half of that , so R = 11.45

or just under 11 and 1/2 inches