$A$ cube of side $4 \, cm$ contains a sphere touching its sides. Find the volume of the gap in between. (in $, cm^3$)

In the auditorium,there are $20$ cylindrical pillars. Each pillar has a radius of $14 \, cm$ and a height of $5 \, m$. Find the cost of painting the curved surface of all the pillars at the rate of ₹ $120$ per $m^2$.

Monica has a piece of canvas whose area is $551 \, m^2$. She uses it to have a conical tent made,with a base radius of $7 \, m$. Assuming that all the stitching margins and the wastage incurred while cutting amounts to approximately $1 \, m^2$,find the volume of the tent that can be made with it. (in $, m^3$)

Find the total surface area of a cylinder with diameter $28 \text{ cm}$ and height $50 \text{ cm}$. (in $\text{cm}^2$)

The ratio of the surface area of a sphere to the curved surface area of a hemisphere is $9:2$. Find the ratio of their volumes.

State whether the following statement is True or False and justify your answer: If the radius of a cylinder is doubled and its height is halved,the volume will be doubled.