Calculate the number of bricks,each measuring $25 \, cm \times 15 \, cm \times 8 \, cm$,required to construct a wall with dimensions $19 \, m \times 4 \, m \times 5 \, m$,when $10 \%$ of its volume is occupied by mortar.

$A$ ball of lead,$4\, cm$ in diameter,is covered with gold. If the volume of the gold and lead are equal,then the thickness of gold is approximately (in $cm$).
$[$ Given $\sqrt[3]{2} = 1.259 ]$

The height of the right pyramid whose area of the base is $30\, m^{2}$ and volume is $500\, m^{3}$ is ...... $m$.

$A$ cylindrical can with a horizontal base and an internal radius of $3.5 \, cm$ contains sufficient water so that when a solid sphere is placed inside,the water just covers the sphere. The sphere fits exactly into the can. The depth of the water in the can before the sphere was added is:

The curved surface area of a hemisphere is $27.72 \text{ cm}^2$ and its volume is $19.404 \text{ cm}^3$. Find its radius in $\text{cm}$.

$A$ rectangular water tank has dimensions $80\, m \times 40\, m$. Water flows into it through a pipe with an opening area of $40\, cm^{2}$ at a speed of $10\, km/hr$. By how much will the water level rise in the tank in half an hour (in $cm$)?