Question

A cylindrical tank has a capacity of 6160 $m^3$. Find its depth if its radius is 14 m. Calculate the cost of painting its curved surface (outer) at the rate of Rs. 3 per $m^2$.

Answer 1

Volume = $\pi r^{2}h$

=$\frac{22}{7}\times 14\times 14\times h$

Given: Volume = $6160m^3$

Hence $\frac{22}{7}\times 14\times 14\times h=6160$

h = $\frac{6160\times 7}{22\times 14\times 14}$ = 10 m

Now,

Curved surface area = $2\pi rh$

= $2\times \frac{22}{7}\times 14\times 10$

= 880 $m^2$

Cost of painting = Rs.3 per $m^2$

Hence Total cost of painting = $880\times 3$ = Rs 2640