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?

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

= 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 * 80 π = 1100000

n =

=

= 4375

Therefore, each wheel of the car will make 4375 revolutions

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