Question

39. How many cubic metres of earth must be dug out to sink a well 22.5 m deep and off dames
7 m. Also, find the cost of plastering the inner curved surface at 3 per square mete.
OR​

Answer 1

$\huge{\boxed {\mathfrak \pink {\fcolorbox {red}{blue}{AnSwEr}}}}$

__________________________

Volume of earth to be dug = Volume of well

$={22}{7} ×{7}{2} ×{7}{2} × {22.5m}^{3} = {866.25m}^{3}$

Area of the inner curved surface

$= 2πrh </p><p>= 2 ×{22}{7} ×{7}{2} × {22.5m}^{2} = {495m}^{2}$

Hence.. Cost of plastering the inner curved surface =R

Rs(495x3) = Rs 1485.

__________________________