A bag contains six blue marbles and three red marbles. A marble is drawn, it is replaced, and another marble is drawn.What is the probability of drawing a red marble and a blue marble in either order?

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You have 3 choices for the red marbles and 6 choices for the blue marbles. Thus, the probability of drawing a red marble then a blue one is (3*6)/(9*9) = 18/81 = 2/9. (Since there is no replacement, there's 9 choices for each event.)