Question

A closed box is made up of wood which is $1cm$ thick. The outer dimensions of the box is $5cm\times 4cm\times 7cm$. Find the volume of the wood used.

Answer 1

Given outer length $=5$ cm

Outer breadth $=4$ cm

Outer height $=7$ cm

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

$=5\times 4\times 7=140{cm}^3$

Thickness of wooden box, $w=1$ cm

Inner length $=l–2w=5–2=3$ cm

Inner breadth $=b–2w=4–2=2$ cm

Inner height $=h–2w=7–2=5$ cm

Inner volume $=3\times 2\times 5=30{cm}^3$

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

$=140-30=110{cm}^3$