The length, breadth, and height of a cuboid are $30 \, cm$, $20 \, cm$, and $15 \, cm$ respectively. Its volume is $\ldots \ldots \ldots \, cm^3$.

$A$ 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 $0.2$)

$A$ cone is $8.4 \, cm$ high and the radius of its base is $2.1 \, cm$. It is melted and recast into a sphere. The radius of the sphere is (in $cm$):

In a cylinder,if the radius is halved and the height is doubled,the volume will be

Total surface area of a cylinder is equal to:

$A$ well with $14\, m$ inside diameter is dug $50\, m$ deep. Earth taken out of it is spread all around a rectangular field of length $110\, m$ and width $100\, m$. Find the increase in the height of the field (in $cm$).