The diameter of a sphere is decreased by $25\%$. By what per cent does its curved surface area decrease (in $\%$)?

It is required to make a closed cylindrical tank of height $1 \,m$ and base diameter $140 \,cm$ from a metal sheet. How many square metres of the sheet are required for the same (in $,m^2$)? Assume $\pi = \frac{22}{7}$.

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

The inner diameter of a circular well is $3.5 \, m$. It is $10 \, m$ deep. Find its inner curved surface area. [Assume $\pi = \frac{22}{7}$] (in $, m^2$)

$A$ right circular cylinder just encloses a sphere of radius $r$ (see figure). Find:
$(i)$ Surface area of the sphere,
$(ii)$ Curved surface area of the cylinder,
$(iii)$ Ratio of the areas obtained in $(i)$ and $(ii)$.

Curved surface area of a right circular cylinder is $4.4 \, m^2$. If the radius of the base of the cylinder is $0.7 \, m$,find its height. (Take $\pi = \frac{22}{7}$) (in $, m$)