The curved surface area of a hemisphere is $306 \, cm^{2}$. Then its total surface area is $\dots \dots \dots cm^{2}$.

The length,breadth,and height of a cuboid are $20\, cm$,$15\, cm$,and $12\, cm$ respectively. Find its total surface area (in $cm^2$).

The radius of a sphere is increased by $10 \%$. Prove that the volume will be increased by $33.1 \%$ approximately.

The dimensions of a cuboid are in the ratio of $4: 3: 1$. If its total surface area is $3800 \, cm^{2}$,then find its volume in $cm^{3}$.

The length,breadth,and height of a metallic cuboid are $10\, cm$,$6\, cm$,and $4\, cm$ respectively. If the density of the metal is $7.8\, g/cm^3$,find the mass of the cuboid (in $g$).

Find the curved surface area,total surface area and volume of a hemisphere of diameter $42\, cm$.