Question

Find the cost of sinking a tube well $280m$ deep, having diameter $3m$ at the rate of $Rs.3.60$ per cubic meter. Find also the cost of cementing its inner curved surface at $Rs.2.50$ per square meter.

Answer 1

Given: The diameter of the well is $3m$ and it is $280m$ deep.

$\therefore$ Volume of cylinder $=\pi r^{2}h$
$=(\frac{22}{7}\times {\left(\frac{3}{2}\right)}^2\times 280)m^3=1980m^3$
Cost of sinking the tube well
$=$ Volume $\times$ cost per cubic meter
$=Rs.3.60\times 1980=Rs.7128$

Inner curved surface area of the well $=2\pi rh$
$=(2\times \frac{22}{7}\times \frac{3}{2}\times 280)m^2$
$=2640m^2$

The cost of cementing the inner $C.S.A$
$=Rs.(2.50\times 2640)=Rs.6600$

Hence, the cost of sinking and cementing are $Rs.7128$ and $Rs.6600$ respectively.