maths

(5.8X50+7.2X30+0.3X20+2.5X100)/(50+30+20+100)
=782/200
=3.91

2008-01-02 18:13:31 補充：
frizen8講得好岩,而且佢個問題好唔掂,佢話『甲用$5.8買50個橙』,甘係每個橙5.8定係5.8就買到50個橙呢?

2008-01-02 18:14:45 補充：
如果要100個橙呢...甘試下甘啦 [(5.8X50 7.2X30 0.3X20 2.5X100)/(50 30 20 100)]/2=[782/200]/2=3.91/2=1.955

甲用$5.8買50個橙
乙用$7.2買30個橙
丙用$0.3買20個橙
丁用$2.5買100個橙???
加埋有200個橙,
你問這100個橙平均每個幾錢? ,
你條問題有錯誤!!

(5.8X50+7.2X30+0.3X20+2.5X10)/100

=(290+216+6+250)/100
=762/100
=7.62