如图1,点P在线段AB上时,∵AB=6, AP PB =2,∴AP=6× 2 1+2 =4,PB=AB-AP=6-4=2,∵点Q为PB的中点,∴PQ= 1 2 PB=1,∴AQ=AP+PQ=4+1=5;如图2,点P在线段AB的延长线上时,∵AB=6, AP PB =2,∴ 6+BP BP =2,解得BP=6,∵点Q为PB的中点,∴BQ= 1 2 BP=3,∴AQ=AB+BQ=6+3=9,综上,线段AQ的长为5或9.