Because there is no trigram that represents the number 5, people with the gua number 5 would take on the same characteristics as gua 2 and gua 8.
Specifically, a man with gua 5 would take on the attributes of kua 2. And a woman with gua 5 would take on the characteristics of gua 8.
This does not mean that they have their life guas changed from 5 to 2 or 8.
They still have the gua 5. Just that their attributes follow that of 2 and 8.
They both belong to the west group in Ba Zhai.