The Fellowship consisted of nine members: four Hobbits, two Men, one Elf, one Dwarf, and one wizard. Is there a specific in-Universe explanation for:
I have seen un-cited references that it was because there were 9 Nazgûl. What I'm looking for (if that's true) is specific in-Universe reference/citation.
Specific make-up (how many of whom)?
Frodo (Ring-bearer by fortune), Boromir (Gondor's representative), Aragorn (being the King/Isildur's Heir/bearer of the Andúril) and Gandalf (duh!) seem like they are there for a good reason.
I suppose Elf and Dwarf are there for Affirmative Action (e.g. make sure every Good Guy race gets to contribute to the fight). Citation needed if this is the case!
The other 3 hobbits seem like... well... WHY? (yes they come in handy later, but why did Elrond let them in initially?)