Concept:This is a hypergeometric distribution problem, since oranges are drawn without replacement from a mixed lot containing defective and good oranges.
Explanation:Let
X denote the number of defective oranges drawn when 3 oranges are selected.
X can take the values
0,1,2,3.
There are
4 defective and
16 good oranges, so the total number of oranges is
4+16=20.
Total number of ways to choose 3 oranges from 20 is
(320​).
Using the hypergeometric probability formula:
P(X=r)=(320​)(r4​)(3−r16​)​, for
r=0,1,2,3.
Now calculate each probability:
P(X=0)=(320​)(316​)​=5728​P(X=1)=(320​)(216​)(14​)​=198​P(X=2)=(320​)(116​)(24​)​=958​P(X=3)=(320​)(34​)​=2851​The sum of all probabilities is
1, confirming a valid probability distribution.
Answer:The probability distribution of defective oranges is:
P(X=0)=5728​,
P(X=1)=198​,
P(X=2)=958​,
P(X=3)=2851​.