I’ll give the benefit of the doubt that maybe
@waterbottle10 is a CA3 and quite honestly it took me a minute to get this concept down.
First learn this curve and commit it to memory.
Then understand this chart and notice the correlation.
FA/FI is close to 1, which correlates to a low blood:gas coefficient, which means faster induction agent. So let's answer the question of why Sevo is a better (faster) induction agent than Iso. (A real world example)
Sevo has a blood: gas coefficient of 0.65 vs Iso of 1.4.
Higher blood: gas coeffcient = high lipophilicity = higher solubility
High solubility means MORE anesthetic needs to UPTAKE to the blood to get the brain to do it's thing. Therefore the onset is slower.
This why SEVO is a faster induction agent than Isoflurane (which is why when you do peds inhaled inductions you use Sevoflurane)
So to really answer the question
@waterbottle10 is asking. Higher FA/FI means LOWER solubility (requires less uptake) and fast action to the brain and therefore faster induction.