$A$ solid cone of height $24 \, cm$ and base radius $8 \, cm$ is melted to form a solid cylinder of radius $6 \, cm$ and height $6 \, cm$. In the whole process,what percent of material is wasted (in $\%$)?

$A$ large cube is formed from the material obtained by melting three smaller cubes of $3, 4$ and $5 \, cm$ side. What is the ratio of the total surface areas of the smaller cubes and the large cube?

$A$ $3.3\, m$ high room is half as long again as it is wide and its volume is $123 \frac{3}{4}\, m^3$. Find its length and breadth.

The radius of a cylinder is made twice as large. How should the height be changed so that its volume remains unchanged?

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:

The radius of a cylinder is increased by $20 \%$,keeping its height unchanged. What is the percentage increase in its volume?