Q: Two pipes A and B can fill a cistern in 8 and 12 minutes respectively, and a third pipe C can empty it in 15 minutes. How long will it take to fill the cistern if all the three are opened at the same time?\nOptions:\n(A) 17 1/17 min\n(B) 28 1/7 min\n(C) 17 1/7 min\n(D) 17 1/8 min\n(E) 17 5/7 min Let's give some random thoughts before answering.
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1/8 + 1/12 - 1/15 = 17/120\n120/17 = 7 1/17
Therefore, the answer is (A).
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