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)

  1. 0.528
  2. 5.28
  3. 52.8
  4. 528
Anurag Mishra Professor Asked on 26th October 2015 in Maths.
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1 Answer(s)

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

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.

Monis Rasool Professor Answered on 28th October 2015.
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