Question

Find the number of metallic circular disc with $1.5cm$ base diameter and of height $0.2cm$ to be melted to form a right circular cylinder of height $10cm$ and diameter $4.5cm$.

Answer 1

Let, the radius of cylinder =$R$ and the height is =$H$

and the radius of cylinder =$r$ and the height is =$h$

So,

Volume of cylinder $=n\times$ Volume of circular disc

$\pi R^{2}H=n\times \pi r^{2}h$

$\pi \times \left(2.25{)}^2\right(10)=n\times \pi (1.75{)}^2\left(0.2\right)$

$n=\frac{50.625}{0.1125}=450$