Question

What will be the cost of cementing the inner surface of a well which is 22 m deep and 6 m in diameter at the rate of Rs. 21 per meter square?
1. Rs. 6512
2. Rs. 8712
3. Rs. 4516
4. Rs. 6731

Answer 1

Correct Answer - Option 2 : Rs. 8712

Given

Height of well = 22 m

Diameter of well = 6 m

Concept

Curved surface area of well = 2πrh

Calculation

Curved surface area of well = 2 × (22/7) × 3 × 22

Cost of cementing = 2 × (22/7) × 3 × 22 × 21

⇒ Rs. 8712