To the sustained applause of family and friends, 15 new firefighter-medics graduated from the Fairfax County Fire and Rescue Academy last Friday night. Five of the new recruits are assigned to fire stations in Mason District, which are among the busiest in the county. The recruits began their training last October, and successfully completed a rigorous course of physical and academic activities that resulted in an average score of 92 percent for the class as a whole.