Question

How many cublic metres of Earth much be dug out to sink a well which is 7 m deep and of diameter 28 m. Find the cost ofplasterinhg itsbcurved surface 3.50 per square.m.

Answer 1

volume of earth dug out = volume of cylinder

$22 \div 7 \times 7 \times 14$
= 22× 14
$308cm^{2}$

cost of plastering curved surface area is

csa of cylinder× 3.5

$2 \times\pi \times 14 \times 7 \times 3.5$
= 2×2×3.5
= Rs 14