Question

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

Answer 1

Given

Radius of cylinder $r=\frac{70}{2}=35cm$

Height of cylinder $h=10cm$

Radius of disc $r_1=1cm$

Height of disc $h_1=0.5=\frac{1}{2}cm$

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

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

$=38500c{m}^3$

Volume of small disc $=\pi r_1^2{h}_1$

$=\frac{22}{7}\times 1\times 1\times \frac{1}{2}$

$=\frac{11}{7}c{m}^3$

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

$=24500$