Marbles of diameter $1.4 \,cm$ are dropped into a cylindrical beaker of diameter $7 \,cm$ containing some water. Find the number of marbles that should be dropped into the beaker so that the water level rises by $5.6 \,cm$.

If a marble of radius $2.1 \, cm$ is put into a cylindrical cup full of water of radius $5 \, cm$ and height $6 \, cm$,then how much water flows out of the cylindrical cup? (in $cm^3$)

If the radius of a sphere is doubled,its volume becomes $\ldots \ldots \ldots$ times the volume of the original sphere.

$A$ building is in the form of a cylinder surmounted by a hemispherical dome (see figure). The base diameter of the dome is equal to $\frac{2}{3}$ of the total height of the building. Find the height of the building,if it contains $67 \frac{1}{21} \, m^3$ of air. (in $m$)

$A$ mason constructs a wall of dimensions $270 \,cm \times 300 \,cm \times 350 \,cm$ with bricks each of size $22.5 \,cm \times 11.25 \,cm \times 8.75 \,cm$. If $\frac{1}{8}$ of the total volume of the wall is occupied by mortar,find the number of bricks used to construct the wall.

$A$ solid piece of iron in the form of a cuboid of dimensions $49 \, cm \times 33 \, cm \times 24 \, cm$ is moulded to form a solid sphere. The radius of the sphere is (in $cm$):