#### Question

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 traveling at a speed of 66 km per hour? [Use Π = 22/7]

#### Solution

Diameter of the wheel of the car = 80 cm

Radius (*r*) of the wheel of the car = 40 cm

Circumference of wheel = 2π*r*

= 2π (40) = 80π cm

Speed of car = 66 km/hour

= (66x100000)/60 cm/min

= 110000 cm/min

Distance travelled by the car in 10 minutes

= 110000 × 10 = 1100000 cm

Let the number of revolutions of the wheel of the car be *n*.

*n *× Distance travelled in 1 revolution (i.e., circumference)

= Distance travelled in 10 minutes

n x 80Π = 1100000

`n = (1100000xx7)/(80xx22)`

= (35000)/8 = 4375

Therefore, each wheel of the car will make 4375 revolutions.

Is there an error in this question or solution?

Solution 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 traveling at a speed of 66 km per hour? Concept: Perimeter and Area of a Circle.