Probability

For any events $E$ and $F:$

• $0\le P(E)\le 1$
• $P(\textrm{certain event})=1$
• $P(\textrm{impossible event})=0$
• $P(E')=1-P(E)$
• $P(E \textrm{or} F)=P(E\cup F)=P(E)+P(F)-P(E\cap F).$