The area of the base of a cylinder is $616\,cm^{2}$. Then,the radius of the base of the cylinder is $\ldots \ldots \ldots \ldots cm.$

$A$ metallic sphere with radius $18 \,cm$ is melted and recast to produce cylinders with radius $3 \,cm$ and height $12 \,cm$. Find the number of cylinders produced.

Write 'True' or 'False' and justify your answer:
$A$ solid ball is exactly fitted inside a cubical box of side $a$. The volume of the ball is $\frac{4}{3} \pi a^{3}$.

Total surface area of a cylinder with radius $7 \, cm$ and height $13 \, cm$ is $\ldots \ldots \ldots \ldots \, cm^{2}$.

The $CSA$ of a cone with radius $7\, cm$ and slant height $15\, cm$ is $\ldots \ldots \ldots \, cm^2$.

$A$ plumbline (sahul) is the combination of (see figure):