The radius of a spherical balloon increases from $7 \, cm$ to $14 \, cm$ as air is being pumped into it. Find the ratio of surface areas of the balloon in the two cases.

Find the volume of a sphere whose radius is $7 \, cm$. Assume $\pi = \frac{22}{7}$.

$A$ hemispherical bowl is made of steel,$0.25 \, cm$ thick. The inner radius of the bowl is $5 \, cm$. Find the outer curved surface area of the bowl. (in $, cm^2$)

The students of a Vidyalaya were asked to participate in a competition for making and decorating penholders in the shape of a cylinder with a base,using cardboard. Each penholder was to be of radius $3 \,cm$ and height $10.5 \,cm$. The Vidyalaya was to supply the competitors with cardboard. If there were $35$ competitors,how much cardboard was required to be bought for the competition (in $,cm^2$)? $\left[\text{Assume } \pi = \frac{22}{7}\right]$

Find the surface area of a sphere of diameter $14 \, cm$.
Assume $\pi = \frac{22}{7}$. (in $, cm^2$)

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