Proving Independence of A & B: Probability Proof

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SUMMARY

The discussion centers on proving the independence of events A and B under the condition that P(A|B) equals P(A|B'). The participants utilize foundational probability equations, specifically P(A|B) = P(A∩B) / P(B) and P(A|B') = P(A∩B') / P(B'). The conclusion drawn is that if these two conditional probabilities are equal, it leads to the relationship P(A∩B) / P(B) = P(A∩B') / P(B'), confirming the independence of A and B through established probability principles.

PREREQUISITES
  • Understanding of conditional probability
  • Familiarity with probability notation, including intersections and complements
  • Knowledge of the independence of events in probability theory
  • Ability to manipulate and equate probability equations
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  • Study the concept of event independence in probability theory
  • Learn how to derive conditional probabilities using Bayes' Theorem
  • Explore the implications of P(A∩B) = P(A)P(B) in various probability scenarios
  • Investigate examples of proving independence with real-world applications
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Students of probability theory, mathematicians, and anyone involved in statistical analysis who seeks to understand the principles of event independence and conditional probabilities.

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Homework Statement



Prove if P(A|B) = P(A|B') then A and B are independent.

where B' is the complement of B

Homework Equations



if independent, P(A|B) = P(A)
also, P(A∩B) = P(A)P(B)

for conditional probability,
P(A|B) = P(A∩B) / P(B)

The Attempt at a Solution



P(A|B) = P(A∩B) / P(B) = P(B|A)P(A) / P(B)
P(A|B') = P(A∩B') / P(B') = P(B'|A)P(A) / P(B')

I'm not really sure how to go from here... What do I do?
 
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If you know that P(A|B) = P(A|B') and

P(A|B) = P(AB)/P(B) and P(A|B') = P(AB')/P(B')

(where AB = A intersect B)

then why not set these right-hand sides equal and see what happens?

--Elucidus
 
Yeah, I did that. Then P(A∩B) / P(B) = P(A∩B') / P(B') where ∩ means intersection

Sorry, I still don't see what should follow.
 
Last edited:

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