posted by Nate Williams .
Malia puts together six 4-by-4-by-1 inch square layers with 1-inch cubes, then stacks
them up to form a rectangular prism. This prism rests on a wooden table, on its square
base. All the 1-inch cubes Malia used are white except one, which is red. As a reduced
fraction, what is the probability that the red cube is visible if it is located at random?