See two documents: Sims, W.H. and Truss, A.R., A Reexamination of the Normalization of Armed Services Vocational Aptitude Battery (ASVAB) Forms 6, 7, 6E, and 7E (Alexandria, VA: Center for Naval Analyses, September 1980); and Laurence, J.H. and Ramsberger, P.F., Low-Aptitude Men in the Military: Who Profits, Who Pays? (New York: Praeger, 1991).
The Armed Forces Qualification Test (AFQT) covers four sections from the Armed Services Vocational Aptitude Battery (ASVAB): Word Knowledge, Paragraph Comprehension, Arithmetic Reasoning, and Mathematics Knowledge. These four sections and your scores on them make up the Military Entrance Score, also known as the AFQT. Your AFQT score is used to determine your eligibility for entrance into the Armed Services.
The Armed Forces Qualification Test (AFQT) is used by all of the Services to determine if an applicant is eligible for the military. Four of the ASVAB subtests are combined to form the AFQT. It measures general cognitive ability and is composed of verbal and mathematics subtests. AFQT scores are grouped into categories for reporting purposes. The table below shows the AFQT categories and the percentile score ranges corresponding to the categories. Applicants that score in AFQT category IIIA or higher may qualify for enlistment incentives.