# Find the Speed of the Car (in km/hr) :

The diameter of each wheel of a car is 70 cm. If each wheel rotates 400 times per minute, then the speed of the car (in km/hr) is (take p=22/7)

- 0.528
- 5.28
- 52.8
- 528

**Answer is (3): 52.8**

**Explanation:-
**The diameter of each wheal of a car = 70 cm

**Formula-**

The perimeter of wheel = π x diameter of wheel

The perimeter of wheel = π x diameter of wheel

Then, the perimeter of wheel = 70 x 22/7

= 220 cm

1 m = 100 cm

Then, 1 cm = 1/100 m

Then, the perimeter of wheel = 220/100 = 2.20 m

The distance covered by wheel in a round = the perimeter of wheel = 2.20 m

Therefore, the distance covered by wheel in 400 round = 2.20 x 400

= 880 m

Then, the speed of the car = 880 m/minute

The speed of car in km/hr = 880 x 60/1000

= 52.8 km/hr

Then, the speed of the car = 52.8 km/hr

Hence, the answer is (3) 52.8 km/hr.