The Cannon-balls riddle
A ship sailor has stacked cannon-balls in two tetrahedral pyramids. In order to impress the ship captain he decided to combine the cannon-balls in both of the pyramids and create one large pyramid. The smallest number of cannon-balls he can have if the two pyramids are the same size is twenty ( we assume that he uses every cannon-ball in both pyramids).You can see that solution in the picture below.

However if the two smaller pyramids are different sizes what would be the minimum number of cannon-balls he could use to make one larger tetrahedral pyramid?
|