If the diameter of a sphere is decreased by $25 \%$,its curved surface area will be decreased by (in $\%$).

$A$ solid cylinder has a total surface area of $231 \, cm^2$. Its curved surface area is $(2/3)$ of the total surface area. Find the volume of the cylinder (in $cm^3$).

$A$ solid cylinder has a total surface area of $462 \, cm^2$. Its curved surface area is $\frac{1}{3}$ of its total surface area. The volume of the cylinder is.......$cm^3$.

$A$ cone and a cylinder having the same area of the base have also the same area of curved surfaces. If the height of the cylinder is $2 \, m$,find the slant height of the cone (in $m$).

What is the length (in metre) of the longest rod that can be placed in a room which is $2$ $metre$ long,$2$ $metre$ broad,and $6$ $metre$ high?

$A$ cylindrical can with a horizontal base and an internal radius of $3.5 \, cm$ contains sufficient water so that when a solid sphere is placed inside,the water just covers the sphere. The sphere fits exactly into the can. The depth of the water in the can before the sphere was added is: