單項(xiàng)選擇題

9名大學(xué)生每月的手機(jī)話費(fèi)支出(單位:元)分別是:64.3,60.4,77.6,51.2,53.1,57.5,53.9,47.8,53.5。手機(jī)話費(fèi)支出的平均數(shù)是()

A.53.9
B.57.7
C.55.2
D.56.5

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