$A$ hall is $15 \ m$ long and $12 \ m$ broad. If the sum of the areas of the floor and the ceiling is equal to the sum of the areas of the four walls,the volume of the hall is: (in $m^3$)

$A$ solid cone is $25 \ cm$ high and the radius of its base is $50 \ cm$. It is melted and recast into a solid sphere. Determine the surface area of the sphere (in $cm^2$).

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

$A$ solid piece of iron of dimensions $49 \times 33 \times 24 \text{ cm}$ is moulded into a sphere. The radius of the sphere is......$\text{cm}$.

Assume that a drop of water is spherical and its diameter is $\frac{1}{10} \text{ cm}$. $A$ conical glass has a height equal to the diameter of its rim. If $32,000$ drops of water fill the glass completely,then the height of the glass (in $\text{cm}$) is:

$A$ $1 \, m^3$ of metal weighing $90 \, Kg$ is rolled into a square bar $9 \, m$ long. An exact cube is cut off from the bar. How much does it weigh? (in $kg$)