4. The wheels of a car are of diameter 80 cm each. How many complete revolutions does each wheel make in 10 minutes when the car is travelling at a speed of 66 km per hour?
Let the number of revolution of the wheel be n.
The circumference of the wheel is given by:
Now, the speed of the car is given by:
Thus, the distance travelled in 10 minutes is:
According to the question, we get:
or
Hence, the number of revolutions made by the wheel is 4372.