Probability Flashcards
What does P(AnB) mean?
Probability both occuring
P(A) x P(B)
What does P(AuB) mean?
Probability A or B or both occuring
How to find P(AuB) tho?
P(A) + P(B) - P(AnB)
P(A’) means whats
Probability A doesn’t occur
1 - P(A)
P(B’) means what?
Probability B doesn’t occur
1 - P(B)
- Provide more notes, this is too obscure.
- Add like questions and examples and what to be aware of n shi
Yaa
Main part of this topic?
The venn diagram
I mean from what i see, it’s just the typical fraction thing, with the total at the denominator and the remaining at the numerator n shi. My book too obscure bro
¯_(ツ)_/¯
In a Venn diagram of P(A), P(B) Or P(AnB)
What does P(A) mean?
Probability of what’s within A specifically that’ll occur
So literally, EVERYTHING that’s in A even if it intersects
In a Venn diagram of P(A), P(B) Or P(AnB)
What does does P(B) mean?
Probability of what’s within B specifically that’ll occur
So literally, EVERYTHING that’s in B even if it intersects
In a Venn diagram of P(A), P(B) Or P(AnB)
What does P(A’) mean?
(Vice versa for P(B’))
Probability of what’s not within A specifically that’ll occur
So u get all the numbers outside of A, and don’t include the ones that intersect with A
In a Venn diagram of P(A), P(B) Or P(AnB)
How would u find P(A’)?
(Vice versa for P(B’))
U do 1 minus P(A)
for example if P(A) = 0.8
P(A’) = 1 - 0.8 = 0.2
All probabilities are usually between 0 and 1
In a Venn diagram of P(A), P(B) Or P(AnB)
What does P(A or B or both) mean?
IN DATA BOOKLET
P(AuB)
The issue is that, following the way of understanding P(A) and P(B)
Technically, we have the intersection twice therefore we have the formula:
P(AuB) = P(A) + P(B) - P(AnB)
In a Venn diagram of P(A), P(B) Or P(AnB)
What does P(A and B) mean then?
Intersection of P(A) and P(B) specifically (not including just the A or B, if u know u know)
Course, hoping that the question given we may have the intersection
In addition, will help for finding P(AuB)
In a Venn diagram of P(A), P(B) Or P(AnB)
How would u find P(AuB)?
So all numbers within A, within B and within intersection of A and B
In a Venn diagram of P(A), P(B) Or P(AnB)
How would u find P(AnB)?
Only within intersection of P(A) and P(B)
What does independent mean?
(A and B are independent)
NOT IN DATA BOOKLET
A does not affect the likelihood of B happening and vice versa
So in terms of Venn diagram, they can intersect
and in addition, a formula:
P(AnB) = P(A) x P(B)
What does mutually exclusive mean
(A and B are mutually exclusive)
When A cannot happen at the same time as B
Therefore in a supposed Venn diagram, they wouldn’t intersect
in addition, ya use the formula:
P(AnB) = P(A) x P(B) and must equal zero
so!
P(AnB) = 0, that makes sense ¬.¬
How to find if it’s independent?
Say u do actually have a number within intersection
X the numbers within circles (although they may intersect, remember what P(A) means, everything within that circle)
IF it doesn’t equal the intersect, it is not independent
P(AnB) = P(A) x P(B)
How about probability with replacement?
Four cards from a regular pack of 52 playing cards are picked randomly from the deck. Find the probability that all four are aces…
4/52 x 4/52 x 4/52 x 4/52 = 256/7311616 = 1/28561
= 0.0000350 to 3sf
How about probability without replacement?
Four cards from a regular pack of 52 playing cards are picked randomly from the deck. Find the probability that all four are aces…
4/52 x 3/51 x 2/50 x 1/49 = 24/6497400 = 1/270725
= 0.00000369 to 3sf (smaller than with replacement)
How to use tree diagrams?
If only I can add pictures for free.
Sound super obscure but, gaining probability after the first probability is done. There can be multiple after the first one. In addition, be aware what they ask for the question. There’s a possibility that even after u got ur answer, u may have to x it multiple times to gain the true answer
(the true if u know, u know)
Do ya know about two way tables???
¯_(ツ)_/¯
If it’s mutually exclusive, what it mean for P(AuB)?
P(AuB) = P(A) + P(B)
There’s no P(AnB) cuz it’s zero
