A well has to be dug out that is to be 22.5 m deep and of diameter 7 m. Find the cost of plastering the inner curved surface at Rs. 3 per sq.meter :

A. Rs. 1465

B. Rs. 1475

C. Rs. 1485

D. Rs. 1495

Answer: Option C

Solution(By Examveda Team)

Curved surface area :
$$\eqalign{ & = 2\pi rh \cr & = \left( {2 \times \frac{{22}}{7} \times \frac{7}{2} \times 22.5} \right){{\text{m}}^2} \cr & = 495{\text{ }}{{\text{m}}^2} \cr} $$
∴ Cost of plastering :
= Rs. (495 × 3)
= Rs. 1485