conditional probability
A/B are event, when B
happen, A
‘s conditional probability. ps.P(B) > 0
seven ball in p1
p2
two white ball in p1
one white ball in p2
What’s the probability when fetch white from B bucket.
Event A
is fetch white
Event B
is fetch from P2
bucket
Multiplication formula
formula
when n >= 2 :
full probability formula
if event array B1, B2, B3, … satisfying
- i ≠ j
- i,j=1 2 ….
then array event is a divide of sample space Ω
.
this formula mean no interference event array can calculate target sample space in divide.
It’s called prior probability
For example: spot check a set of different products’ good rate
bayes formula
bayes formula is the reverse process of full probability formula.
It research a happened event cause factor, not forcast it.
It’s called posterior probability
For example:
find killer in criminal suspect
spam filtering in e-mail system