Question

The pillars of an apartment are in a cylindrical shape. If each pillar has a circular base of radius 40 cm and height 20 m, then how much concrete would be required to build 7 such pillars?

• A. 7040
• B. 70.4
• C. 704
• D. 7.04

Answer 1

The correct option is B

70.4

Radius of base of cylinder = 40 cm
Height of cylinder = 20m = 2000 cm
Volume of single cylinder $=\pi r^{2}h=\frac{22}{7}\times 40\times 40\times 2000$

$=\frac{70400000}{7}c{m}^3$
Converting $c{m}^{3}to{m}^3$

$1cm={10}^{-2}m$
$1c{m}^3={10}^{-6}{m}^3$
$\therefore 70400000c{m}^3=70.4m^3$

$=\frac{70400000}{7}c{m}^3$ $=\frac{70.4}{7}{m}^3$
Thus, volume of 7 such pillars = Volume of one such pillar x 7 $=\frac{70.4}{7}\times 7=70.4m^3$