Question

The inner diameter of a well is 4.20 metre and its depth is 10 metre. Find the inner surface area of the well. Find the cost of plastering it from inside at the rate Rs.52 per sq.m.

Answer 1

by applying formula
$2\pi \times 2.1 \times 10 + 2\pi \times 2.1 {}^{2}$
surface area=159.65
for cost =159.65×52=8302.09

Answer 2

Answer:

Surface area = 159.5748 square cm

Cost of plastering it from inside = 8297.88 per square meter

Step-by-step explanation:

The inner diameter of a well = 4.20 m

So radius = 4.20/ 2 m

r = 2.1 m

depth = h = 10m

We have to find the inner surface area of the well

$Surface \ area = 2\pi r^2 + 2\pi rh$

$=2 \times 3.14 \times (2.1)^2 + 2 \times 3.14 \times 2.1 \times 10\\ = 27.6948 + 131.88\\= 159.5748 cm^2$

Surface area = 159.5748 square cm

Cost of plastering it from inside be

= 52 × 159.5748

= 8297.88 per square meter

Cost of plastering it from inside = 8297.88 per square meter