The radius of a sphere is decreased by $20 \% .$ By what per cent does its curved surface area decrease (in $\%$)?

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

Find the curved surface area and the total surface area of a hemisphere with a radius of $14\, cm$.

$A$ small village, having a population of $5000$, requires $130\, \text{litres}$ of water per head per day. The village has an overhead cuboidal tank measuring $20\, \text{m} \times 13\, \text{m} \times 10\, \text{m}$. For how many days will the water of this tank last?

The length,breadth,and height of a cuboidal box are $30 \, cm$,$20 \, cm$,and $8 \, cm$ respectively. Find the lateral surface area of the cuboidal box (in $cm^2$).

The diameter of a solid sphere is $14 \, cm$. Find its surface area in $cm^2$.