$1 \text{ litre} = \ldots \ldots \ldots \text{ cm}^3$

$A$ village,having a population of $4000$,requires $150$ litres of water per head per day. It has a tank measuring $20 \,m \times 15 \,m \times 6 \,m$. For how many days will the water of this tank last?

$A$ conical tent is made from a piece of cloth with an area of $165 \, m^{2}$. The radius of the base of the tent is $5 \, m$.
$(i)$ If one student occupies an average of $\frac{5}{7} \, m^{2}$ of ground area,how many students can sit in the tent?
$(ii)$ Find the volume of the cone.

The surface area of a sphere with a radius of $5 \, cm$ is five times the curved surface area of a cone with a radius of $4 \, cm$. Find the height and volume of the cone (take $\pi = \frac{22}{7}$).

Find the curved surface area and the total surface area of a hemisphere with a radius of $2.1 \, m$.

Rain water which falls on a flat rectangular surface of length $6\, m$ and breadth $4\, m$ is transferred into a cylindrical vessel of internal radius $20\, cm$. What will be the height of water in the cylindrical vessel if the rainfall is $1\, cm$? Give your answer to the nearest integer. (Take $\pi = 3.14$) (in $cm$)