Question

A metal cylinder with height $10cm$ and the diameter of base $70cm$ is melted to make a number of small discs with radius $1cm$ and thickness $0.5cm$. How many such discs could be made from the cylinder?

• A. $24400$ discs.
• B. $23500$ discs.
• C. $24500$ discs.
• D. $22500$ discs.

Answer 1

The correct option is C $24500$ discs.

Volume of metallic cylinder $=$ $\pi r^{2}h$

$=$ $\frac{22}{7}\times 85\times 35\times 10$

$=$ $38500$ ${cm}^3$

Volume of 1 disc$=$$\pi r^{2}h=\frac{22}{7}\times 1\times 1\times 0.5=\frac{11}{7}{cm}^3$

Number of discs $=$ $\frac{38500}{\frac{11}{7}}=\frac{38500\times 7}{11}=24500$