Find the curved surface area (in $cm^{2}$) of a hemisphere of diameter $28\, cm$.

If the radius of a sphere is doubled,then its surface area is increased by (in $\%$)

The numerical values of the volume and the area of the lateral surface of a right circular cone are equal. If the height of the cone is $h$ and the radius is $r,$ the value of $\frac{1}{h^{2}}+\frac{1}{r^{2}}$ is

The radius of a cylinder is increased by $20 \%$,keeping its height unchanged. What is the percentage increase in its volume?

$A$ solid is hemispherical at the bottom and conical above. If the surface areas of the two parts are equal,then the ratio of the radius and height of its conical part is

From a cubical block of wood of side $1 \, m$,a cylinder of the largest possible volume is carved out. The volume (in $m^3$) of the remaining wood is