Answer:
The problem stats you cannot compress the balls; so you can not round up. You must round down. That means 4 x4 x4. There will be 16 balls per layer and 4 layers. So 48 balls.
The volume of the box is 12%5E3 inches.
You are told the diameter of a ball is 2.5 inches. So the radius of a ball is 1.25 inches
The volume of each ball is %284%2F3%29pi%2Ar%5E3
Subtract the volume of 16 balls from the volume of the box to get the volume of the packing bead material
To get the percentage of beads to box, divide the bead volume by the box volume and multiply by 100%