Adventurer Rings discussion

so if arans get a 105% crit rate with the critical ring if they use SE then its better for them to use the cruel ring which gives 5% ending up with 100% crit chance?

also the example you are giving would sound to me like the first theory

edit:
with the second theory i meant (for examply for my aran)

30% x 90% chance = 27% chance on normal damage
30% x 10% chance = 3% chance on ring crit on normal damage
70% x 10% chance = 7% chance on ring crit on normal crit
70% x 90% chance = 63% chance on normal crit without ring crit

this is using 70% base crit without any other critical source but the critical ring