Question

The diameter of the wheel of a car is 70cm. How many revolutions will it make to travel 1.65km?

Answer 1

The circumference of a circle is Pi x Diameter 

C = Pi x D 

C = 3.14 x 70cm 

C = 220cm 

Next convert 220cm to km = 220 / 100000 = 0.0022 km 

1.65km / 0.0022km = 750 revolutions

Answer 2

1.65 km = 1.65 ×1000×100 cm
              = 165000 cm 
now,radius = diameter/2
           = 70/2
           =35 cm
now, circumference = 2π r
                                 = 2×(22/7)×35
                                 = 220 cm
it means, 220 cm = 1 revolution
       then, 165000 cm = 165000/220
                                   = 750 revolution