Pipe A can fill a tank in 5 hours, pipe B in 10 hours and pipe C in 30 hours. If all the pipes are open, in how many hours will the tank be filled?\nOptions:\n(A) 5\n(B) 4\n(C) 3\n(D) 6\n(E) 8 Let's think first. Stream of consciousness:
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Part filled by A + B + C in 1 hour = 1/5 + 1/10 + 1/30 = 1/3\nAll the three pipes together will fill the tank in 3 hours.
So, the answer is (C).
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