(1)甲=(45+44+48+42+57+55+66)÷7=51千克 乙=(48+44+47+54+51+53+60)÷7=51千克 ∴甲、乙水果平均每天销售51千克;
(2)S甲2=[(45-51)2+(44-51)2+(48-51)2+(42-51)2+(57-51)2+(55-51)2+(66-51)2]= S乙2=[(48-51)2+(44-51)2+(47-51)2+(54-51)2+(51-51)2+(53-51)2+(60-51)2]=24 ∵S甲2>S乙2 ∴乙水果销售更稳定些. |