Kai is optimizing a desk bookend. Goal: hold at least 6 books while using the least base width. Test data (each design was tested the same way): - add a non-slip rubber bottom: books held = 6 books; base width (lower is better) = 10 cm - make the base narrower: books held = 4 books; base width (lower is better) = 7 cm - add a heavier base plate: books held = 8 books; base width (lower is better) = 12 cm - use smooth plastic bottom: books held = 3 books; base width (lower is better) = 10 cm