In Plato’s system of education, you will complete at minimum 18 years of sports, music, and poetry with 2 years in military service. If students fail to complete the 20 years, they will be assigned to “producer” status which works in producing primary needs for society such as farming and agriculture.
If they finish the 20 years, they will take the exam and be assigned “auxiliary” status which handles military duties if they fail the exam. Those who pass this examination will take 10 years of additional mathematical education and sit for a second exam, after which they will either sit on the advisory board for philosopher kings (if they fail the exam) or take an additional 5 years of moral philosophy (if they pass) and go on to be appointed philosopher king.