A conditional probability is one where an extra condition is added. For instance, if you have a bag with 15 red beads and 12 blue beads, the chance of getting a red bead is 15/27 and the chance of getting a blue bead is 12/27. But if I asked what the chances of getting a red bead or a blue bead after the first bead is taken and shown to be red, you would get 14/26 for getting a red bead, and 12/26 for getting a blue bead. The notation for a conditional statement is