Volume Questions

A hemispherical bowl is made of a steel sheet $0.8\text{cm}$ thick. The inside radius of the bowl is $5\text{cm}$. The volume of steel used in making it is approximately:

The lateral surface area of a right circular cone is three times the volume of that cone. If the height and the radius of the cone are $h\text{units}$ and $r\text{units}$ respectively, then $\frac{1}{h^2}+\frac{1}{r^2}$ is equal to:

If the radius and height of a cone are each increased by $10\%$, then the volume of the cone is increased by: