The average U.S. Army Ranger School student is in the rank of E-4 through E-6 on the enlisted side and O-1 through O-3 for the officers. Most are between 19 and 27 years old, and only about 21 Airmen graduate each year. Then there are candidates like 39-year-old Chief Master Sgt. William Speck, who in April, became the first Air Force chief master sergeant to graduate from Ranger School.
http://www.af.mil/News/ArticleDisplay/tabid/223/Article/778657/chief-becomes-first-af-e-9-to-graduate-ranger-school.aspx Michael Bottoms