Question

The inner diameter of a circular well is 4.2 m. It is 20 m deep. Find (i) the inner curved surface area (ii) the cost of plastering this curved surface at the rate of Rs. 50 per m².

Answer 1

Answer:

Curved surface area of well = 264 m².

Cost of plastering =13,200 Rs

Step-by-step explanation:

The inner diameter of a circular well is 4.2 m.

Inner radius of well r= 2.1 m

Depth/height of well = 20 m

(i)Find the inner curved surface area:

Curved surface area of Circular well

$= 2\pi \: rh \\ \\ = 2 \times \frac{22}{7} \times 2.1 \times 20 \\ \\ = 44 \times 0.3 \times 20 \\ \\ = 44 \times 6 \\ \\ = 264 \: {m}^{2}$

(ii) The cost of plastering this curved surface at the rate of Rs. 50 per m².

Cost of plastering per m² = 50 Rs

Cost of plastering of 264 m² = 264×50

=13,200 Rs

Hope it helps you.