For example, in a bag of 2 red balls and 2 blue balls (4 balls in total), the probability of taking a red ball is formula_26; however, when taking a second ball, the probability of it being either a red ball or a blue ball depends on the ball previously taken. For example, if a red ball was taken, then the probability of picking a red ball again would be formula_27, since only 1 red and 2 blue balls would have been remaining.