Beverly needs to make a container in the shape of a rectangular prism that holds 1000 in squared of liquid

If you need to find dimensions of rectangular prism that has volume 1000 units, start by writing the formula for rectangular prism: height×length×width=volume.
Then calculate - cubic root of 1000: ∛1000=10. 
So, the cubic prism will have these dimensions: 10×10×10.
To make it a rectangular prism, just change one (or two if you would like) of the dimensions, and solve for one: 1000=10×Y×20, Y=5.
Conclusion - there can be many different dimensions for rectangular prisms, but the one I solved for has these: 10×20×5.

Hope this helps :)