Find the curved surface area of a cylinder whose height is $35 \, cm$ and radius of the base is $15 \, cm$. (in $cm^2$)

The length of a metal hollow cylinder is $70\, cm$. If the radius of the hollow inside it is $10\, cm$ and the metal thickness is $1\, cm$,find the difference between the areas of the outer and inner curved surfaces.

Write True or False and justify your answer.
$A$ right circular cylinder just encloses a sphere of radius $r$ as shown in the figure. The surface area of the sphere is equal to the curved surface area of the cylinder.

$A$ 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 $, cm^2$)

The surface area of a sphere is $2464 \, cm^2$. Find its diameter in $cm$.

The radius of a sphere is increased by $10 \%$. Prove that the volume will be increased by $33.1 \%$ approximately.