Final answer:
The correct ranking by density, excluding Earth, from highest to lowest would be Mercury, Venus, Mars, Neptune, Uranus, Saturn, and Jupiter.
Step-by-step explanation:
To rank the planets (excluding Earth) by average density, we need to understand that terrestrial planets are generally denser than gaseous giants.
Given the average density of Jupiter at 1.3 g/cm³ and Uranus and Neptune at densities of 1.3 g/cm³ and 1.6 g/cm³ respectively, we can infer their place in the ranking.
The terrestrial planets (Mercury, Venus, and Mars), have higher densities. Thus, the correct order from highest density to lowest would be Mercury, Venus, Mars, Neptune, Uranus, Saturn, and Jupiter.