Question

The radii of two circular ends of a frustum shaped dust bin are $15$cm and $8$cm. If its depth is $63$cm, find volume of the dust bin.

Answer 1

Given $r_1=15$cm, $r_2=8$cm, $h=63$cm
Volume of the dustbin (frustum)$=\frac{1}{3}\pi h(r_1^2+r_2^2+r_1{r}_2)$
$=\frac{1}{3}\times \frac{22}{7}\times 63({15}^2+8^2+15\times 8)$
$=\frac{1}{3}\times \frac{22}{7}\times 63(225+64+120)$
$=66\times 409=26,994$
$\therefore$ Volume of the dustbin$=26,994c{m}^3$.