Question 1178387
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Imagine each ball packed in its own cube 1.5 cm on a side.  Then the array of those cubes in the box that is 6 cm by 3 cm by 3 cm is 4 by 2 by 2.  So there are 16 balls in the box.<br>
You can picture solving the problem by finding the free space in each of those cubes containing a sphere and multiplying that by 16.<br>
ANSWER: 16 times the difference between the volume of a cube with edge 1.5 cm and the volume of a sphere with diameter 1.5 cm.<br>
You can do the calculations....<br>