Question

find the volume of wood used to make a closed box of inner dimensions of 30 cm multiplied by 20 cm multiplied by 18 cm the thickness of wood being 1 cm

Answer 1

Answer:

Now, the volume of wood= (32×21×20)-(30×20×18)=13440-10800=2640cm²

Answer 2

$\large\underline\purple{\bold{Solution :- }}$

Internal Dimensions of the box.

• Length of box, l = 30 cm

• Breadth of box, b = 20 cm

• Height of box, h = 18 cm

Thus,

We know that,.

• Internal volume of box is given by

$\longmapsto \: \rm \: Volume_{(internal)} = l \times b \times h$

$\rm :\implies\:Volume_{(internal)} = 30 \times 20 \times 18$

$\rm :\implies\: \boxed{ \pink{ \rm{Volume_{(internal)} = 10800 \: {cm}^{3} }}}$

Now,

• as thickness of the box = 1 cm

So,

External Dimensions of the box

• Length of box, L = 30 + 2 = 32 cm

• Breadth of box, B = 20 + 2 = 22 cm

• Height of box, H = 18 + 2 = 20 cm

Thus,

• External volume of the box is given by

$\longmapsto \rm \: \:Volume_{(external)} \: = 32 \times 22 \times 20$

$\rm :\implies \boxed{ \pink{ \rm{\:Volume_{(external)} \: = \: 14080 \: {cm}^{3} }}}$

Now,

• Volume of wood is given by

$\bf\:Volume_{(wood)} \: = \: Volume_{(external)} - Volume_{(internal)}$

$\rm :\implies\:Volume_{(wood)} = 14080 - 10800$

$\rm :\implies\: \boxed{ \pink{ \bf \: Volume_{(wood)} \: = \: 3280 \: {cm}^{3} }}$