Question

Find the number of metallic circular discs 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

Required number of metallic discs = (Volume of right circular cylinder)/(Volume of one metallic circular disc)

$=\frac{\pi {\left(\frac{4.5}{2}\right)}^2\times 10}{\pi {\left(\frac{15}{20}\right)}^2\times 0.2}$

$=(2.25{)}^2\times \frac{400}{225}\times 50$

$=\frac{225}{100}\times \frac{225}{100}\times \frac{400}{225}\times 50=450$