✔ 最佳答案
P(X = 0)
= 8C2 / 10C2
= (8!/6!2!) / (10!/8!2!)
= (8!)² / 6!10!
= 28/45
P(X = 1)
= 2C1 x 8C1 / 10C2
= (2!/1!1!) x (8!/7!1!) / (10!/8!2!)
= 16/45
P(X = 2)
= 2C2 / 10C2
= (2!/2!0!) / (10!/8!2!)
= 1/45
P(X = 3)
= 0
2012-12-02 12:47:22 補充:
在 10 個樣本中,其中有 2 個不合格。超幾何分佈描該 10 個樣本中抽出 2 個,其中 X 個是不合格的機率:
若 X ≤ 2,則:
P(X) = f(X; 10, 3, 2) = C(2,X) * C(10-2, 2-X) / C(10,2)
若 X > 2,則:
P(X) = 0
2012-12-02 12:54:11 補充:
應是:抽出「3」個。