Probability rules are essential for calculating the likelihood of occurrences in various scenarios. The multiplication rule applies when determining the probability of two dependent events happening together, with the formula P(
mutually exclusive or disjoint
the events do not occur the
the same
Event
An event is a subset of a sample space
Formulas of Probability
Distribution
Subtraction Rule
Key word: At least one
The subtraction rule also known
as the complement rule is when an
event is NOT occurring.
P(A) = 1 - P(A')
Multiplication Rule
Key word: And
In multiplication A and B are two
dependent events. Multiplication is
used when the probability of events A and B
occurs are equal. The is event A times event B occurs, which A is given.
P(A and B) = P(A) P(B|A)
Addition Rule
Key word: Or
In addition the event A or event B occurrences are equal to the probability. The formula is event A plus event B minus the probability of both A and B events.
P(A or B)= P(A) + P(B)-P(A and B)
or
Mutually exclusive or Disjoint:
P(A or B)= P(A) + P(B)