The height of a right circular cylinder is $6 \, m$. $3$ times the sum of the areas of its two circular faces is equal to twice the area of its curved surface. The radius of the base is ...... $m$.

How many coins,$2 \, mm$ thick and $1.5 \, cm$ in diameter,should be melted in order to form a right circular cylinder with base diameter $6 \, cm$ and height $8 \, cm$?

The area of the iron sheet required to prepare a cone $24 \text{ cm}$ high with base radius $7 \text{ cm}$ is .......... $\text{cm}^2$ (Take $\pi = \frac{22}{7}$)

The base of a right pyramid is a square,and the length of the diagonal of the base is $24 \sqrt{2} \text{ m}$. If the volume of the pyramid is $1728 \text{ m}^3$,its height is ......... $\text{m}$.

Water is flowing at the rate of $5 \text{ km/h}$ through a pipe of diameter $14 \text{ cm}$ into a rectangular tank which is $50 \text{ m}$ long and $44 \text{ m}$ wide. The time taken,in hours,for the rise in the level of water in the tank to be $7 \text{ cm}$ is:

$2\, cm$ of rain has fallen on a $1\, km^2$ of land. Assuming that $50\%$ of the raindrops could have been collected and contained in a pool having a $100\, m \times 10\, m$ base,by what level would the water level in the pool have increased? (in $m$)