A well of diameter 3m is dug 14m deep. The earth taken out

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A well of diameter 3m is dug 14m deep. The earth taken out of it has been spread evenly all around it in the shape of a circular ring of width 4m to form an embankment. Find the height of the embankment.

Volume of the earth taken out

= πr²h = π ×		3		²	× 14
		2

=	63	π cubic metre
	2

Ex–radius of embankment =	3	+ 4 =	11	metre
	2		2

∴Volume of embankment = π(R² – r²) × h₁

= π			11		²	-		3		²		× h₁
			2					2

= π		11	+	3			11	-	3		× h₁
		2		2			2		2

= π × 7 × 4h₁
= 28πh₁ cu. metre

∴ 28πh₁ =	63	π
	2

&rArr4; h₁ =	63	= 1.125 metre
	2 × 28