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.

The surface area of a sphere is $7850 \, cm^2$. Find its radius in $cm$. (Use $\pi = 3.14$)

The length,breadth,and height of a hall are $7\, m$,$5\, m$,and $4\, m$ respectively. It has two doors measuring $3\, m \times 2\, m$ each and four windows measuring $2\, m \times 1\, m$ each. Find the cost of whitewashing all the four walls and the ceiling of the hall at the rate of ₹$200$ per $m^2$.

There are two boxes of metal sheet. The length,width,and height of a cuboidal box are $30 \, cm$,$25 \, cm$,and $20 \, cm$ respectively. $A$ cubical box has each edge of $25 \, cm$. Find out which box requires more metal sheet and by how many $cm^2$?

The curved surface area of a cylinder is $4400 \, cm^2$ and its base has a radius of $14 \, cm$. Find the volume of the cylinder in $cm^3$.

$A$ right triangle with sides $6 \, cm$,$8 \, cm$,and $10 \, cm$ is revolved about the side $8 \, cm$. Find the curved surface area of the solid so formed (in $cm^2$). (in $, cm^2$)