[文商] 統計-96-淡江-保險

[middleroad (勤學統計)]

Suppose there are two boxes. Box I contains 20 articles, of which 5 are
defective, and box II contains 30 articles, of which 6 are defective.

One article is randomly selected from each box, and the selections from the
two boxes are independent. Let X denote the total mumber of defective articles
obtained. Determine the probability distribution of X.

X→Bin(n=2,p=1/20)

請問　n=2跟p=1/20是怎麼求出來的呢？

謝謝～

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→ a016258:答案不對吧...>.<"
→ middleroad:是喔　那麼這題要怎麼算呢
推 cutebodlol:就X=0,1,2的狀況跟機率都寫出來就好
→ middleroad:但是我有點看不懂題意　不知道過程怎麼解的
推 kerota:P(X=0)=0.75*0.8=0.6  P(X=1)=0.75*0.2+0.25*0.8=0.35
→ kerota:P(X=2)=0.25*0.2=0.05
推 STREETPOP:K大正解