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题目内容
（概率论与数理统计(一)）
已知离散型随机变量X的可能值为x1=-1,x2=0,x3=1,且EX = 0 . 1 , DX = 0 . 8 9 , ) .
( A ) P = 0 . 4 , P 2 = 0 . 1 , P 3 = 0 . 5 :
( B ) P 1 = 0 . 1 , P 2 = 0 . 1 , P 3 = 0 . 5
( C ) = 0 . 5 , P 2 = 0 . 1 , P 3 0 . 4 :
( D ) P 1 0 . 4 , P 2 = 0 . 5 , P 3 = 0 . 5 .
( A ) P = 0 . 4 , P 2 = 0 . 1 , P 3 = 0 . 5 :
( B ) P 1 = 0 . 1 , P 2 = 0 . 1 , P 3 = 0 . 5
( C ) = 0 . 5 , P 2 = 0 . 1 , P 3 0 . 4 :
( D ) P 1 0 . 4 , P 2 = 0 . 5 , P 3 = 0 . 5 .
参考答案