I see. So if I'm understanding correctly, if the unit is also in the 5-star normal pool, like Ryoma for instance during a focus banner with Ryoma & 2 others, then P(Ryoma) = 1 / 3 × 3% + 1/# of 5-star Red Characters in Pool (30) × 3% = 1% + 0.1% = 1.1%. And then P(Ryoma given red) = 1.1% / 31.15% = 3.53% assuming another red in the focus & the character pools remaining the same from your calculation.
Not that I don't believe you, this seems legit. Just wondering how you found/got the info & why it appears the majority of people still think the way I did in the Past.