Question

The cost of painting the total surface area of a cone at $25paise/{cm}^2$ is $Rs176$. Find the volume of the cone, if its slant height is $25cm$.

Answer 1

slant height is $25cm$

Cost of painting is $Rs.176$

Total surface area of a cone is $\frac{176\times 100}{25}=704c{m}^2$

$⟹\pi r(h+r)=704$

$⟹\frac{22}{7}(r^2+25r)=704⟹r=7cm$

Volume of the cone is $\frac{1}{3}\pi r^{2}h=\frac{1}{3}\times \frac{22}{7}\times (7{)}^2\times (25)=1283.33c{m}^3$