$A$ matchbox measures $4 \,cm \times 2.5 \,cm \times 1.5 \,cm.$ What will be the volume of a packet containing $12$ such boxes (in $,cm^3$)?

If the volume of a right circular cone of height $9 \, cm$ is $48 \pi \, cm^3$,find the diameter of its base. (in $, cm$)

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 $, m$)

$A$ 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 $, m^{2}$)

Find the volume of a sphere whose radius is $0.63 \, m$. Assume $\pi = \frac{22}{7}$. (in $, m^3$)

Find $(i)$ the curved surface area and $(ii)$ the total surface area of a hemisphere of radius $21\, cm$.