A rectangle prism has length of 20 inches, a width of 2 inches and height of 3 1/4 inches. The prism is filled with cubes that have edge lengths of 1/4 inches. How many cubes are needed to fill the rectangle?

The first thing we must do is find the volume of the rectangular prism which will be given by:

Vtotal = (20) * (2) * (3 1/4)

Votal = 130 in ^ 3

We now look for the volume of each individual cube:

Vcube = (1/4) ^ 3

Vcube = 1/64 in ^ 3

The number of cubes will be:

N = (Vtotal) / (Vcube)

N = (130) / (1/64)

N = 8320

Answer:

to fill the rectangle are needed 8320 cubes