A.9.2%×8.6%×7.1%×7.5%×8% B.(9.2%×8.6%×7.1%×7.5%×8%)-100% C.109.2%×108.6%×107.1%×107.5%×108% D.(109.2%×108.6%×107.1%×107.5%×108%)-100%
A.27.78 B.1.26 C.1.39 D.1.25
A.對變量求平均數(shù) B.對指標求平無數(shù) C.對標志求平均數(shù) D.對標志值求平均數(shù)