Question

The inner diameter of a circular well is $3.5m$. It is $10m$ deep. Find
$\left(i\right)$ its inner curved surface area
$\left(ii\right)$ the cost of plastering the curved surface at the rate of $Rs.40$ per $m^2$

Answer 1

Given:

$\Rightarrow$(i)$r=$ radius$=\frac{3.5}{2}=1.75$ , $h=$ depth of the well$=10m$

$\Rightarrow$Curved surface area

$=2\pi rh$

$=(2\times \frac{22}{7}\times 1.75\times 10)m^2=110m^2$

$\Rightarrow$(ii) Cost of plastering $=$ Rs $40$ per $m^2$

The cost of plastering the curved surface $=$ Rs $(110\times 40)=$ Rs $4400.$