The radius of a 80 cm wide road roller is 77 cm. Find the number of revolutions that the roller will take to cover an area of 96.8 $$\text{m}^2$$​. [Takе π = $$\frac{22}{7}$$] 

Correct option is A

Given:

Width of the road roller = 80 cm

Radius of the roller = 77 cm

Area to be covered = 96.8 m²= 968000 cm²

Use π = $$\frac{22}{7}$$​​

Formula Used:
Lateral surface area of cylinder (1 revolution) = $$2\pi r h$$​​
Where:

r = radius of roller

h = width of roller

Number of revolutions = $$\frac{\text{Total area to be covered}}{\text{Area covered in one revolution}}$$​​

Solution:
Lateral surface area per revolution = $$2 \times \frac{22}{7} \times 77 \times 80$$​​

​$$= 2 \times \frac{22}{7} \times 77 \times 80$$​​

​$$= \frac{44}{7} \times 77 \times 80$$​​

​$$= \frac{44 \times 77 \times 80}{7}$$​​

= 38720 cm²

Number of revolutions = $$\frac{968000}{38720}$$​ = 25

The roller will take 25 revolutions to cover the area