Families making $200K+ do 400 points higher than families making $40K or $20K or less. I forget the exact figure. This study is widely available. 400 point diff

Families making $200K+ do 400 points higher than families making $40K or $20K or less. I forget the exact figure. This study is widely available. 400 point difference is so massive it shows it’s not largely an intelligence test nor is it resistant to prep.