Question

The diameter of a road roller is 40 cm. It is 70 cm long. What is the area of levelled surface, when it rolls once?

• A. $2200{\text{cm}}^2$
• B. $17600{\text{cm}}^2$
• C. $4400{\text{cm}}^2$
• D. $8800{\text{cm}}^2$

Answer 1

The correct option is D

$8800{\text{cm}}^2$

Radius of roller (r) $=\frac{40}{2}=20\text{cm}$

Length of roller $=70\text{cm}$

Area of levelled surface when it rolls once = curved surface area

$=2\pi rh$

$=2\times \frac{22}{7}\times 20\times 70$

$=8800{\text{cm}}^2$