$A$ cylindrical jar of diameter $24\, cm$ contains water to a height of $30\, cm$. $A$ spherical steel ball is dropped into the jar and the level of the water rises by $67.5\, mm$. The diameter of the ball is......$cm$.

$A$ 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:

The circumference of one end of a frustum of a right circular cone is $48\, cm$ and of the other end is $34\, cm$. If the height of the frustum is $10\, cm$,its volume (in $cm^3$) is

$A$ solid sphere of radius $1 \, cm$ is melted to convert into a wire of length $100 \, cm$. The radius of the wire (using $\sqrt{3} = 1.732$) is ......... $cm$.

$A$ hall is $15 \ m$ long and $12 \ m$ broad. If the sum of the areas of the floor and the ceiling is equal to the sum of the areas of the four walls,the volume of the hall is: (in $m^3$)

The height of a circular cylinder is increased $6$ times and the base area is decreased to $\frac{1}{9}$ of its value. The factor by which the lateral surface area of the cylinder increases is