Question

The slant height and base diameter of a conical tomb are $25$m and $14$m respectively. Find the cost of white-washing its curved surface at the rate of $Rs.210$ per $100$m${}^2$.

Answer 1

Given:

Slant height,$l=25$m

and, diameter $=14$ m

So, radius, $r=\frac{14}{2}m=7$m,

$\Rightarrow$Curved surface area $=\pi rl$

$=(\frac{22}{7}\times 7\times 25)$m${}^2$

$=550$m${}^2$

$\Rightarrow$Cost of white washing $100m^2$ area $=$ Rs.$210$

$\Rightarrow$Cost of white washing $550m^2$ area $=$ Rs. $\frac{210\times 550}{100}$

$=$ Rs.$1155$

Hence, the cost of white washing is $Rs.1,155$