Good questions from Asimov. But just like with car repair, he didn’t know this subject. It has been a field of study for a while, and researchers have worked directly on this core problem defining general intelligence distinct from specific knowledge.

This Veritassium video is a balanced overview of the topic: https://youtu.be/FkKPsLxgpuY?si=iY7QBEQK1DkzNhxI

Needless to say, no, the IQ test is not a conspiracy by people who are good at number sequence problems to keep themselves in charge of the world.