- Conditional probability - P(A|B) / P(B|A) = P(A) / P(B) - the ration of area in a venn diagram
- if there are 30 people in a room the probability of a common birthday is close to 70%
- P(A ∩ B) = P(A) P(B|A) = P(A) . P(B)
- P(A ∪ B) = P(A) + P(B) - P(A ∩ B)
Random variable = count.
Probability is like measuring a frequency.
Expected value is sum of xi * pi = np for binomial distributions.
Poison distribution is binomial distribution tending towards inf.
An event can occur 0, 1, 2, … times in an interval. The average number of events in an interval is designated lambda.