I don’t know if they are the “official” definitions, but they work effectively.
I am not faulting your calculations or logic.
Isn’t it true however that IQ is flawed?
It’s perfectly possible for people who do well on IQ tests to be throughly stupid in most other matters and conversely low IQ people being witty and engaging, with sharp minds.
It is supposed to be best when the subject is unaware they are being tested for IQ.
In my opinion, Fat is convinced he is smart and thinks this means he doesn’t need to put the work in.
Most IQ tests are pretty good nowadays, and give you a good rough estimate of the person's intelligence. Tested IQ correlates too well with things like academic achievement, career, ability to do certain things well etc. to not be an atleast decent measure of intelligence.
That doesn't mean that school losers have to be low-IQ however. Very High IQ individuals are school-losers reasonably often, because the system was not designed for them.
We do not know Pat's IQ, but you can estimate someones intelligence pretty well by how they talk, write, act, reason and if they have detailed knowledge in one ore several things.
Patrick has only surface knowledge on most topics, he is often wrong on topics he should specialize in as a sci-fi writer, he writes grammatically correct and has a decent vocabulary (most of the time, atalker), he is highly repetitive in his statements, he seldom has original thoughts, he seems to have little curiosity and no patience for any disagreement.
My highly professional diagnosis is therefore that Patrick has average Intelligence, maybe slightly above average.
He was probably either surrounded by people that were dumber than him as a kid, or was constantly told that he was special and gifted by his parents.
I assume his abysmal performance in High-School results in him being lazy, but not being able to still have decent grades with minimal effort because he was not intelligent enough for it.