Question

Find the volume of the frustum cone whose base and top radius is 4 mm and 2 mm respectively. The height of the cone is 27 mm. (Use $\pi$ = 3.14).

• A. 781.28 mm${}^3$
• B. 791.28 mm${}^3$
• C. 761.28 mm${}^3$
• D. 711.28 mm${}^3$

Answer 1

The correct option is B 791.28 mm${}^3$

Volume of the frustum cone is $V=\frac{\pi h}{3}(R^2+Rr+r^2)$
$R=4mm,r=2mm,h=27mm$
$V=(3.14\times 27)/\left(3\right)[4^2+4\times 2+2^2]$
$=3.14\times 9[16+8+4]$
$=28.26\left[28\right]$
$=791.28m{m}^3$