$A$ small village, having a population of $5000$, requires $130\, \text{litres}$ of water per head per day. The village has an overhead cuboidal tank measuring $20\, \text{m} \times 13\, \text{m} \times 10\, \text{m}$. For how many days will the water of this tank last?

The diameter of a solid hemisphere is $21 \, cm$,then its volume is $\ldots \ldots \ldots \, cm^3$.

$A$ cylindrical roller $2.5\, m$ in length and $1.75\, m$ in radius,when rolled on a road,was found to cover an area of $5500\, m^{2}$. How many revolutions did it make?

The diameter of a solid sphere is $14 \, cm$. Find its surface area in $cm^2$.

The edge of a cube is $35\, cm$. Find the total surface area of the cube (in $cm^2$).

Metal spheres,each of radius $2 \, cm$,are packed into a rectangular box of internal dimensions $16 \, cm \times 8 \, cm \times 8 \, cm$. When $16$ spheres are packed,the box is filled with preservative liquid. Find the volume of this liquid. Give your answer to the nearest integer. [Use $\pi = 3.14$] (in $cm^3$)