$A$ cuboidal box measures $25 \, cm \times 15 \, cm \times 8 \, cm$. Find its total surface area (in $cm^2$).

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

The radius of a cone is $10\, cm$ and the total surface area of a cone is $880\, cm^2$. Find the slant height in $cm$. (Use $\pi = 22/7$)

The radius and height of a cylinder are $10 \, cm$ and $20 \, cm$ respectively. Find the volume of the cylinder. $(\pi = 3.14)$ (in $cm^3$)

The radius and height of a cylindrical cistern are $70 \,cm$ and $1.5 \,m$ respectively. How many litres of water can it hold?

If $V$ is the volume of a cuboid of dimensions $a, b, c$ and $S$ is its total surface area,then prove that $\frac{1}{V} = \frac{2}{S} \left( \frac{1}{a} + \frac{1}{b} + \frac{1}{c} \right)$.