The floor of a rectangular hall has a perimeter of $250\, m$. If the cost of painting the four walls at the rate of $10$ per $m^2$ is $Rs. 15000$,find the height of the hall. (in $, m$)

Twenty-seven solid iron spheres,each of radius $r$ and surface area $S$,are melted to form a single sphere with surface area $S'$. Find the ratio of $S$ to $S'$.

$A$ heap of wheat is in the form of a cone whose diameter is $10.5\, m$ and height is $3\, m$. Find its volume. The heap is to be covered by canvas to protect it from rain. Find the area of the canvas required. (in $, m^{2}$)

$A$ godown measures $60 \,m \times 25 \,m \times 15 \,m$. Find the maximum number of wooden crates each measuring $1.5 \,m \times 1.25 \,m \times 0.5 \,m$ that can be stored in the godown.

The volume of a right circular cone is $9856 \, cm^3$. If the diameter of the base is $28 \, cm$,find the slant height of the cone. (in $, cm$)

Find the volume of the right circular cone with radius $3.5 \, cm$,height $12 \, cm$. Assume $\pi = \frac{22}{7}$. (in $, cm^3$)