§6.3抽样分布 a0=2=2x2o=r ;1 i=1 i=1 ③)E()=E2X-1=2EX)-E(X) i=1 =1(D(X)+(E(X,))-(DX)+(E(XP) =2a2+)-(。2+)="1。 ④E(S)=E(2”1)=”=o 7/512 1 2 2 1 2 1 1 1 ( ) 1 ) 1 (2) ( ) ( n n D X n X n D X D n i n i i n i i ( ) ( ) 1 ] 1 (3) ( ) [ 2 1 2 1 2 2 2 E X E X n X X n E B E n i i n i n i ( ( ) ( ( )) ) ( ( ) ( ( )) ) 1 2 2 1 D X E X D X E X n i n i i 2 2 2 1 2 2 1 ) 1 ( ) ( 1 n n n n n i 2 2 2 2 ( ) 1 ) 1 (4) ( ) ( n n E Bn n n B n n E S E §6.3 抽样分布 7/51