Legendary average chance to pull?

Games Halo 5: Guardians
#1

How many gold REQ should you buy before you get a rare or legendary permanent?

What is the average chance to get one?

#2

I’ve spent $105 on gold REQs alone and not a single permanent legendary to account for it. But I have 60+ scorpions and numerous other helpful equipment so I ain’t even mad.

#3

I’m SR42, I must have opened over 50 of them and only got 2 Legendaries which were both Warzone: AI kills boosts…