Thread: Theorycrafting: The likelihood of drawing SR and SSR kamihime in Gatcha

Originally Posted by sanahtlig

Also, we know the rarity rates exactly; they don't need to be estimated.

This misunderstanding happens frequently so I've revised the table to try and be clearer.

Also, I have no idea where you're getting the 50% chance of SSR kamihime from 3.3 rolls. My spreadsheet currently shows that a 50% rate is achieved at 4.8 10-rolls.

1. Where are the exact rates?
2. The 50% from 3.3 rolls is from your 4th/5th tables in your OP, where it states 3.3 rolls $98 for 50% chance of SSR Kamihime. Using 1.1% SSR Kamihime probability, 50% occurs at the 63rd roll, not 48th roll.
Formula is 1 - (1 - r)^n = p
where:
r = rate per pull
n = number of pulls
p = probability of at-least 1 pull of r rate

- - - Updated - - -

Formula is 1 - (1 - r)^n = p

So if we want to isolate n...
(1 - r)^n = (1 - p)
n * log(1 - r) = log(1 - p)
n = log(1 - p) / log(1 - r)
n = log(50%) / log(98.9%) = -0.30102999566398119521373889472449/-0.00480370840282059472713473451959
n = 62.666167556553876882697804745512

Originally Posted by Unregistered

1. Where are the exact rates?
2. The 50% from 3.3 rolls is from your 4th/5th tables in your OP, where it states 3.3 rolls $98 for 50% chance of SSR Kamihime. Using 1.1% SSR Kamihime probability, 50% occurs at the 63rd roll, not 48th roll.
Formula is 1 - (1 - r)^n = p

1. The game states that the SSR rate is 3%.
2. I multiply that 3% by the category rate for kamihime in the SSR tier (47.83%). That equals a SSR kamihime rate of 1.43%, not 1.1%. That's likely why our end results are different.