Probability

Probability of an event

Keywords: probability of an event, impossible event, sure event, independent event

PA=AΩ

|A| - number of ways an event can happen

|Ω| - total number of outcomes

PAB=PA+PB-PAB

Probability of an impossible event

P=0

Probability of a sure event

PΩ=1
PA¯=1-PA
PAB=PA|B·PB=PB|A·PA

In cas events A and B are independent

PAB=PA·PB