Mario was riding a bicycle with wheels 26 inches in diameter

Mario was riding a bicycle with wheels 26 inches in diameter. During 1 minute of Mario's ride, the wheels made exactly 200 revolutions. At what average speed, in feet per second, was Mario riding during that minute?

  1. 65π/9
  2. 65π/18
  3. 130π/9
  4. 845π/18
  5. 1690π/9

Answer

The correct answer is A.

Mario will travel a distance equal to 1 circumference of the wheel for each complete revolution of the wheel.

Circumference of Mario's wheel, C = πD, where D is the diameter of the circle.

Hence, C = 26π inches

Speed = Distance / Time

Distance for 200 revolutions in ft = 26π x 200 x 1/12

Time in sec = 60

So, speed =  (26π x 200)/(12 x 60)

= 65π/9