Question

The inner diameter of a circular well is $3.5m$. It is $10m$ deep and area of the playground is $1584m^2$
Find the cost of plastering this curved surface at the rate of Rs.$40$ per $m^2$.

• A. Rs.$4400$
• B. Rs.$3400$
• C. Rs.$2400$
• D. Rs.$4300$

Answer 1

The correct option is A Rs.$4400$

The well is in the shape of a cylinder. Curved Surface Area of a Cylinder of Radius "R" and height "h" $=2\pi Rh$

Hence, CSA of the well $=2\times \frac{22}{7}\times \frac{3.5}{2}\times 10=110sqm$

Cost of plastering at Rs $40$ per sq m $=110\times 40=Rs4400$