The multiplication rule is used for finding the probability that event A occurs in a first trial and event B occurs in a second trail.
P(A and B)
Now to determine the value of the probability of A and B, we need to figure out if the events are independent or dependent.
Independent : The outcome of one event doesn’t affect the outcome of the other event.
Dependent: If the outcome or occurrence of the first affects the outcome or occurrence of the second so the probability is changed.
Then the probability of A and B is the product of the probability of A occurring times the probability of B occurring after it is determined that event A has already occurred.
P(A and B) = P(A) * P(B)