Define the meaning of Hierarchical Social Structure.

A fundamental aspect of social organization that is established by fighting or display behavior and results in a ranking of the animals in a group. The simplest dominance hierarchies are linear and are known as pecking orders. ... In such a hierarchy the top individual (alpha) dominates all others.

The median is 4 because 2 x’s out 9, 3 x’s out 7, 3 x’s out 5, and 4 is the only remaining number.