Question

The radius of a roller is 0.7 m and it is 2 m long How much area will it cover in 10 revolutions?

• A. $88m^2$
• B. $78m^2$
• C. $80m^2$
• D. $70m^2$

Answer 1

The correct option is A $88m^2$

For one revolution
Curved surface area=$2\pi rh=2\times \frac{22}{7}\times \frac{7}{10}$
For 10 revolutions
Curved surface area=$\frac{2\times 22\times 2}{10}\times 10=88m^2$'