Conditional probability Flashcards
What is P(A|B) read as?
P( of A given B)
What does P(A|B) denotes as?
(2 way)
- The probability event A happening
- given that event B has already happened
If events are independent, how can it be expressed?
(P(A|B) shenanigan)
(2-way)
- P(A) = P(A|B)
- P(AnB) = P(A) x P(B|A)
If events aren’t independent, how it can be expressed?
(P(A|B) shenanigan)
(Must learn)
P(A|B) = P(AnB)/P(B)
In 2 way tables, what must u always do?
Total up everything
…. so then u can ace the questions
What’s one thing u must always be aware of in terms of probability n stuff?
Whether they are independent or not
What does it mean by “without replacement”?
- The certain object gets removed
- Affecting the 2nd probability
- Independent i think
What does it mean by “with replacement”?
- The certain object doesn’t get removed
- “as it’s getting replaced”
- So doesn’t rlly affect probability much
- Not independent?
Everything below:
Refer to Kyle’s notes
Define mutually exclusive
(Heads and tails in 1 coin flip)
(2-way)
- One event cannot occur @
- the same time as the other event
Define independent events
(Heads on 1st flip doesn’t change P(heads))
1 event doesn’t affect the other
Define P(AnB)
(2 things)
- A intersect B
- Venn diagram: the one for both
Define P(AuB)
(2 things)
- A union B
- Venn diagram: the whole thing excluding outside
Define P(A’)
(2 things)
- A compliment
- Venn diagram: everything but A (including the one for both)
Formula for P(AuB) for any probability?
= P(A) + P(B) - P(AnB)
Formula for P(AuB) if mutually exclusive?
= P(A) + P(B)
Formula for P(AnB) if independent?
= P(A) x P(B)
I’d probably wanna spam ppq’s tbh
Possible to remember the rules tho?
