There are 20 balls in a jar. You take out 2 blue balls without putting them back inside, and now the probability of pulling out a blue ball is 1/5. How many blue balls were there in the beginning?\nOptions:\n(A) 12.\n(B) 9.\n(C) 8.\n(D) 7.\n(E) 6. Let's think first. Stream of consciousness:
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12 = 3 blue balls + 18 / 2
So, the answer is (A).
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