A.16.8kJ B.17.2kJ C.23.5kJ D.29.3kJ E.39.5kJ
A.25% B.20% C.15% D.12% E.10%以下
A.單純隨機(jī)抽樣 B.系統(tǒng)抽樣 C.整群抽樣 D.分層抽樣 E.多階段抽樣