$A$ cubical metallic tank whose each edge measures $30\, cm$ is completely filled with water. If $2.7\, litres$ of water is taken out of it, what will be the depth of the remaining water in the tank? (in $cm$)

$2\, cm$ 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 $m$)

$A$ cylinder and a cone have equal radii of their bases and equal heights. If their curved surface areas are in the ratio $8:5$,the ratio of their radius and height is

The perpendicular height of a conical tent is $4 \frac{2}{3} \text{ m}$ and the diameter of its base is $6 \text{ m}$. If $11$ persons can sleep in this tent,find how many average cubic meters $(m^3)$ of air each person gets?

Three spherical balls of radius $2 \, cm$,$4 \, cm$,and $6 \, cm$ are melted to form a new spherical ball. In this process,there is a loss of $25 \%$ of the material. What is the radius (in $cm$) of the new ball?

The diameter of a copper sphere is $18 \, cm$. The sphere is melted and drawn into a long wire of uniform circular cross-section. If the length of the wire is $108 \, m$,the diameter of the wire is ....... $cm$.