Suppose a bag contains 3 red counters and 2 black counters.
A counter is removed at random and then another one is removed
at random. The probability that the second counter is red
depends on (is conditional on) the colour of the first counter
removed.The conditional probability that the second
counter is red, given that the first counter is black is 3/4.
probability is the probability of some event A, given the
occurrence of some other event B. Conditional probability
is written P(A|B), and is read the probability of A, given