Question

Find the volume of the wood used to make a closed box of inner dimensions $30cm\times 20cm\times 80cm$ the thickness of wood being $1cm$.

Answer 1

Given outer length $=30$ cm

Outer breadth $=20$ cm

Outer height $=80$ cm

Outer volume $=$ length $\times$ breadth $\times$ height

$=30\times 20\times 80=48000{cm}^3$

Thickness of wooden box, $w=1$ cm

Inner length $=l–2w=30–2=28$ cm

Inner breadth $=b–2w=20–2=18$ cm

Inner height $=h–2w=80–2=78$ cm

Inner volume $=28\times 18\times 78=39,312‬{cm}^3$

Volume of wood used $=$ outer volume $–$ inner volume

$=48000-39,312‬=8,688{cm}^3$