The curved surface area of a cone with radius $12 \, cm$ and slant height $20 \, cm$ is ....... $\pi \, cm^2$.

$A$ wall $24 \, m$ long,$0.4 \, m$ thick and $6 \, m$ high is constructed with bricks each of dimensions $25 \, cm \times 16 \, cm \times 10 \, cm$. If the mortar occupies $\frac{1}{10}$th of the volume of the wall,then find the number of bricks used in constructing the wall.

The Curved Surface Area $(CSA)$ of a frustum of a cone is given by:

Water is flowing at the rate of $15\, km/h$ through a pipe of diameter $14\, cm$ into a cuboidal pond which is $50\, m$ long and $44\, m$ wide. In what time will the level of water in the pond rise by $21\, cm$? (in $h$)

$A$ metallic sphere with radius $42\, cm$ is melted to cast $8000$ identical balls. Find the radius of these balls (in $cm$).

$A$ tent is cylindrical at the base and conical at the top. Its radius is $1.2\, m$. The height of the cylindrical part is $4\, m$ and the height of the conical part is $3.5\, m$. How many square metres of cloth is used to make the tent?