A.300/350×100/100=85.71% B.200/450×100/100=44.44% C.450/500×100/100=90% D.200/500×100/100=40% E.300/500×100/100=60%
A.分層抽樣 B.系統(tǒng)抽樣 C.整群抽樣 D.單純隨機(jī)抽樣 E.普查
A.雙盲 B.單盲 C.樣本含量 D.三盲 E.隨機(jī)分組