Question 1153539
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In all, there are 5+7+9 = 21 marbles.


Of them, 5 are red and 21-5 = 16 are not red.


Therefore, the probability under the question is


    P = {{{(16/21)*(15/20)*(5/19)}}} = 0.150376.      <U>ANSWER</U>
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Solved.