How many bricks,each measuring $250\, cm$ by $12.5\, cm$ by $7.5\, cm$,will be required to build a $5\, m$ long,$3\, m$ high and $20\, cm$ thick wall?

$A$ cone and a cylinder having the same area of the base have also the same area of curved surfaces. If the height of the cylinder is $2 \, m$,find the slant height of the cone (in $m$).

Consider the volumes of the following:
$1.$ $A$ parallelepiped of length $5\,cm$,breadth $3\,cm$ and height $4\,cm$.
$2.$ $A$ cube of each side $4\,cm$.
$3.$ $A$ cylinder of radius $3\,cm$ and length $3\,cm$.
$4.$ $A$ sphere of radius $3\,cm$.
The volumes of these in decreasing order are:

$A$ cylinder and a cone have their heights in the ratio $2:3$ and the radii of their bases in the ratio $3:4$. Find the ratio of their volumes.

The base of a right pyramid is a square,and the length of the diagonal of the base is $24 \sqrt{2} \text{ m}$. If the volume of the pyramid is $1728 \text{ m}^3$,its height is ......... $\text{m}$.

The circumference of one end of a frustum of a right circular cone is $48\, cm$ and of the other end is $34\, cm$. If the height of the frustum is $10\, cm$,its volume (in $cm^3$) is