$A$ $20\, m$ deep well with diameter $7\, m$ is dug and the earth from digging is evenly spread out to form a platform $22\, m$ by $14\, m$. Find the height of the platform. (in $m$) [Take $\pi=\frac{22}{7}$]

$A$ farmer connects a pipe of internal diameter $20 \,cm$ from a canal into a cylindrical tank in her field,which is $10 \,m$ in diameter and $2 \,m$ deep. If water flows through the pipe at the rate of $3 \,km/h$,in how much time will the tank be filled? (in $minutes$) [Take $\pi = \frac{22}{7}$]

Derive the formula for the volume of the frustum of a cone.

$A$ solid iron pole consists of a cylinder of height $220 \,cm$ and base diameter $24 \,cm$,which is surmounted by another cylinder of height $60 \,cm$ and radius $8 \,cm$. Find the mass of the pole,given that $1 \,cm^3$ of iron has approximately $8 \,g$ mass. (in $kg$) (Use $\pi = 3.14$)

$A$ cubical block of side $7 \, cm$ is surmounted by a hemisphere. What is the greatest diameter the hemisphere can have? Find the surface area of the solid (in $cm^2$). [Use $\pi = \frac{22}{7}$]

$A$ container shaped like a right circular cylinder having diameter $12 \, cm$ and height $15 \, cm$ is full of ice cream. The ice cream is to be filled into cones of height $12 \, cm$ and diameter $6 \, cm$,having a hemispherical shape on the top. Find the number of such cones which can be filled with ice cream. [Take $\pi = \frac{22}{7}$]