Correct Answer - Option 2 : 15
Given:
Radius of circular wheel is 21 m and it need to cover the distance of 1.980 km
Formula used:
Circumference of circle = 2 π r
Number of revolution = Total distance covered/circumference of wheel
Calculation:
When radius of circle is 21 m
∴ Circumference of circle = 2 π × 21 = 132 m
Now, number of revolution required to cover 1.980 km
∴ Number of revolution = 1980/132 = 15
Hence, option (2) is correct