A rectangular container measuring 1m by 2m by 4m is covered with a layer of lead shielding of uniform thickness. Find the thickness of the shielding, to the nearest centimeter, if the volume of the shielding is 3m^3.
Let t be the thickness. Then the box covered in lead has dimensions 1+2t by 2+2t by 4+2t. This can give you an expression for the volume of the box and lead coating. How else can you calculate this volume?