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

The radii of three out of four spheres are $33 \, cm$,$44 \, cm$,and $48 \, cm$ respectively. If the surface area of the fourth sphere is equal to the sum of the surface areas of the first three spheres,find the radius of the fourth sphere (in $cm$).

$A$ school provides milk to the students daily in cylindrical glasses of diameter $7\, cm$. If the glass is filled with milk up to a height of $12\, cm$, find how many litres of milk is needed to serve $1600$ students. (in $0.2$)

Find the total surface area of a cone with diameter $6\, cm$ and slant height $11\, cm$. (in $cm^2$)

For any cone,$l^{2} = \ldots \ldots \ldots$

$A$ shopkeeper has one spherical laddoo of radius $5 \, cm$. With the same amount of material,how many laddoos of radius $2.5 \, cm$ can be made?