Let's analyze the given conditions and evaluate which options are correct.
Given:
- P(X∣Y)=21
- P(Y∣X)=31
- P(X∩Y)=61
Now, let's proceed step by step through each option.
Option A: P(X∪Y)=32
We can use the formula for the union of two events:
P(X∪Y)=P(X)+P(Y)−P(X∩Y)
To find P(X) and P(Y), we use the definitions of conditional probability:
P(X∣Y)=P(Y)P(X∩Y)
21=P(Y)61
P(Y)=61×2=31
Similarly,
P(Y∣X)=P(X)P(X∩Y)
31=P(X)61
P(X)=61×3=21
Now, substituting these values into the union formula:
P(X∪Y)=21+31−61
To add these fractions, we need a common denominator. The common denominator is 6:
P(X∪Y)=63+62−61=64=32
Hence, Option A is correct.
Option B: X and Y are independent
For two events X and Y to be independent, the following condition should hold:
P(X∩Y)=P(X)×P(Y)
We already found that:
P(X)=21
P(Y)=31
P(X∩Y)=61
Checking the independence condition:
P(X)×P(Y)=21×31=61
Since this is equal to P(X∩Y), X and Y are indeed independent.
Hence, Option B is correct.
Option C: X and Y are not independent
From the previous analysis, we have shown that X and Y are independent.
Hence, Option C is not correct.
Option D: P((Xc)∩Y)=31
To find P((Xc)∩Y), we use the fact that:
P(Y)=P((X∩Y)∪(Xc∩Y))
Since (X∩Y) and (Xc∩Y) are disjoint events, we can write:
P(Y)=P(X∩Y)+P(Xc∩Y)
Given:
P(Y)=31
P(X∩Y)=61
Substituting these,
31=61+P(Xc∩Y)
Solving for P(Xc∩Y):
P(Xc∩Y)=31−61=62−61=61
This contradicts Option D, as it says 31.
Hence, Option D is not correct.
In conclusion:
Option A and Option B are correct.
Option C and Option D are not correct.