Probability Equations
P(A U B)=P(A)+P(B)
hint: what sign between a and b?
Mutually exclusive events
the chances of an event occuring
Standard probability
What does P stand for in an equation
Probability of an event
Millie has a bag of marbles, there are 20 in total- 10 red, 6 blue, and 4 green. What is the probability of her choosing a blue marble
30% or 3/10
P( R U G)
probability of R or G
P(A|B)=P(A n B)/P(B)
Conditional Probability
If one thing happens then the other cannot
Mutually exclusive
What does A/B stand for
The options available
after Millie discarded the green marble there were 19 left. What are the chances of her choosing a red marble unrelated to the first outcome?
~52.6%
P( R n G)
Probability of R and G
P(A)= n(A)/n(u)
Probability of an event (standard)
If either happening has no effect on the other
Independent
What does n mean
would it be better to express millie's problem in terms of a venn diagram or a tree diagram?
Tree
P (R)|G
Probability of R given G
P(A n B)=P (A)P (B)
Independent events
The probability of something happening, but only if another thing happens
Conditional Probability
What does U mean
Either option A OR B
Now Millie is down to 18 marbles. What is the probability of her drawing another red marble after drawing the first one? (Now there are 9 red, 6 blue, and 3 green)
25%
P( R U G) | B
Probability of R and G given B
P(A U B)=P(A)+P(B)-P(A n B)
Combined events
Chances of multiple events occuring
Combined events
What does | mean
This given that
What is the probability of Millie drawing a blue marble, placing it back in the bag, then drawing a green marble? (20 in total- 10 red, 6 blue, 4 green)
3%
P(R|G n B)
Probability of R given G and B