Question

the outer dimension of a closed box are 42 CM 30cm and 20 CM if the box is made of wood of thickness 1 cm determine the volume of wood used

Answer 1

consider one face of the rectangular box. so from outer dimension thickness will be subtracted twice to find the inner dimensions

the outer dimensions of the closed box are 42cm , 30 cm and 20 cm.

the thickness of the wood = 1 cm.

to find the inner dimension we will subtract twice the thickness from the outer dimensions.

the inner dimensions of the closed box are 42-2*1=40 cm and 30-2*1 = 28 cm and 20-2*1 = 18 cm

therefore the volume of the wood used

= volume of the external box - volume of the internal box

= 42*30*20 - 40*28*18

=25200-20160

=5040 cubic cm

hope this helps you.