Lucy is making a model of a building by using mold, which is in a shape of rectangular prism and open on one side. It has a length of 18 centimeters, a height of 42 centimeters, and a constant thickness on all sides. The model she constructed has a volume of 6160 cubic centimeters. What is the thickness of the mold?

Question

Lucy is making a model of a building by using mold, which is in a shape of rectangular prism and open on one side.  It has a length of 18 centimeters, a height of 42 centimeters, and a constant thickness on all sides.  The model she constructed has a volume of 6160 cubic centimeters.  What is the thickness of the mold?

Kyle Raeside · Answer

I am having trouble with this story problem.

Steve · Answer

You need a width for the base. Since none is given, I assume the base is an 18x18 square. Assuming that the dimensions are those of the outside of the mold, then if its thickness is x, we have, using the inside dimensions for the volume
(18-2x)^2*42 = 6160
solve that for x.