The radii of two cylinders are in the ratio $2:3$. The ratio of their heights is $5:3$. The ratio of their volumes is:

$A$ cylinder,a hemisphere,and a cone stand on the same base and have the same heights. Find the ratio of their volumes and also the ratio of the areas of their curved surfaces.

Find out the amount of concrete required to erect a concrete pillar whose circular base has a perimeter of $8.8\, m$ and whose curved surface area is $17.6\, m^2$. $\left(\pi=\frac{22}{7}\right)$

$A$ spherical ball of lead,$3 \, cm$ in diameter,is melted and recast into three spherical balls. The diameters of $2$ of these are $1.5 \, cm$ and $2 \, cm$,respectively. The diameter of the third ball is $....... \, cm$.

The capacity of a tank,in the form of a cylinder,is $6160 \, m^3$. If the diameter of its base is $28 \, m$,find out the cost of painting its inner curved surface at the rate of ₹ $2.8$ per $m^2$. (Use $\pi = \frac{22}{7}$)

$A$ solid cylinder having a radius of base as $7 \, cm$ and length as $20 \, cm$ is bisected along its height to get two identical cylinders. What will be the percentage increase in the total surface area?