Question about probability of union

  • Context: Graduate 
  • Thread starter Thread starter St41n
  • Start date Start date
  • Tags Tags
    Probability Union
Click For Summary

Discussion Overview

The discussion centers around the probability of the union of two events defined by inequalities involving positive random variables. Participants explore whether the probability of the union can be expressed in terms of the sum of the random variables.

Discussion Character

  • Technical explanation, Debate/contested

Main Points Raised

  • One participant proposes that the probability of the union of two events A and B can be expressed as P(A U B) = P(x1 + x2 > k).
  • Another participant clarifies that P(A U B) represents the probability that either event A or event B occurs, but does not confirm the proposed relationship with the sum of the random variables.
  • A further response challenges the idea of adding inequalities, stating that it does not work in this context.
  • One participant acknowledges the feedback received regarding the original claim.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the relationship between the union of events and the sum of the random variables, with some asserting that the proposed expression is incorrect.

Contextual Notes

The discussion highlights the complexity of applying probability rules to inequalities and the potential limitations in the assumptions made about the random variables involved.

St41n
Messages
32
Reaction score
0
If x1, x2 positive random variables and we have the following two events:

A={x1 > δ}
B={x2> k-δ}

where 0<δ<k

then is it true that:

P(A U B) = P( x1+x2 > δ+(k-δ)=k ) ?

If true can you explain why is that?
Thank you
 
Last edited:
Physics news on Phys.org
Hi St41n! :wink:

No, P(A U B) means the probability that either A or B is true.

So P(A U B) = P(x1 > 1 or x2 > 1). :smile:
 
yes i know this is the definition of P(A U B), but does it imply anything about the sums when we have inequalities?

Also, I made some changes to my original post. Can you take a look again?
 
St41n said:
… when we have inequalities?

You can't add inequalities like that, it just doesn't work.
Also, I made some changes to my original post. Can you take a look again?

Sorry, still doesn't work.
 
Ok I see, thanks
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
Replies
3
Views
3K
  • · Replies 54 ·
2
Replies
54
Views
7K
  • · Replies 3 ·
Replies
3
Views
3K
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 29 ·
Replies
29
Views
6K