Question

A pen stand is made of wood in the shape of cuboid with three conical depressions to hold the pen.

Answer 1

$\: volume \: of \: cubiod \: = lbh$

$= > 15 \times 10 \times 3.5 = 525cm {}^{2}$

$volume \: of \: 3 \: conical \: depressions \\ = 3 \times \frac{1}{3} \pi \: r {}^{2} h$

$= \pi (0.5) {}^{2} (1.4) = 1.1cm {}^{3}$

$\: volume \: of \: wood \\ = 525 - 1.1 = cm {}^{2}$

$= > 523.9 \: cm {}^{2}$