A well has to be dug out 20 m deep and its radius is 3.5 m. Find the cost of plastering the inner curved surface at ₹5 per square meter.
Answer & explanation
Correct answer: option 2
The inner curved surface area of the well = 2πrh
= 2 × 22/7 × 3.5 m × 20 m
= 440 m²
The cost of plastering the inner curved surface at ₹5 per square meter = 440 × 5 = ₹2,200