解:设要买2.2千克这种茶叶要付x元,500克=0.5千克,50克=0.05千克,0.5:[2.2÷(0.5+0.05)×0.5]=98:x0.5:(2.2÷0.55×0.5)=98:x0.5:(4×0.5)=98:x0.5:2=98:x0.5x=2×980.5x=196x=196÷0.5x=392答:要买2.2千克这种茶叶要付392元。