Thread: volume of box

Find the volume of wood used in making a closed box 20 cm by 12 cm by 9 cm if the wood is 1 cm thick.


answer from book: 900cm^3

L x W x H is the only formula right? how come it is 900 cm^3?

please guide me on this please

That is the formula for the volume of a rectangular solid. A box is not solid! 20x 12 x 9 cubic centimeter is the volume of the box including the interior. Since each side is 1 cm thick, the interior is 18 by 10 by 7 cm.

Originally Posted by HallsofIvy

That is the formula for the volume of a rectangular solid. A box is not solid! 20x 12 x 9 cubic centimeter is the volume of the box including the interior. Since each side is 1 cm thick, the interior is 18 by 10 by 7 cm.

multiplying 18 x 10 7 = 1260 well it is not 900

may i know / see how it looks like

What you want is the volume of the WOOD. To evaluate this, you need to evaluate the volume of the entire amount of space up to the boundaries (i.e. 20 x 12 x 9 = 2160) and subtract the "empty space" (i.e. 18 x 10 x 7 = 1260).