# volume of box

• Nov 18th 2012, 05:20 AM
rcs
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.

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

• Nov 18th 2012, 05:26 AM
HallsofIvy
Re: volume of box
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.
• Nov 18th 2012, 06:15 AM
rcs
Re: volume of box
Quote:

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
• Nov 18th 2012, 07:15 AM
Prove It
Re: volume of box
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).