The ratio of radii of two spheres is $2:3$. Then,the ratio of their volumes is $\ldots \ldots \ldots \ldots$.

$A$ pen stand made of wood is in the shape of a cuboid with four conical depressions and a cubical depression to hold the pens and pins,respectively. The dimensions of the cuboid are $10 \, cm$,$5 \, cm$,and $4 \, cm$. The radius of each of the conical depressions is $0.5 \, cm$ and the depth is $2.1 \, cm$. The edge of the cubical depression is $3 \, cm$. Find the volume of the wood in the entire stand. (in $, cm^3$)

The $CSA$ of a cone with radius $4 \, cm$ and slant height $6 \, cm$ is $\ldots \ldots \ldots \ldots cm^{2}$. (in $\pi$)

The total surface area of a cone is equal to $\ldots \ldots \ldots \ldots .$

The base of a cone with radius $5 \, cm$ and height $12 \, cm$ is hemispherical. Find the total surface area of the article. $(\pi = 3.14)$ (in $cm^2$)

The base of a cone is hemispherical. The radius of the cone is $15 \, cm$ and the total height of the solid is $55 \, cm$. Find the volume of this solid (in $cm^3$).