Question: Working alone, Printers X, Y, and Z can do a certain printing job, consisting of a large number of pages, in 12, 16, and 18 hours, respectively. What is the ratio of the time it takes Printer X to do the job, working alone at its rate, to the time it takes Printers Y and Z to do the job, working together at their individual rates?\nOptions:\n(A)  4/11\n(B)  1/2\n(C)  15/22\n(D)  144/17\n(E)  11/4 Let's think first. Some random reasoning:
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P1 takes 12 hrs\nRate for P2P3 together = 1/16 + 1/18 = 17/144\nTherefore they take 144/17\nRatio = 144/17 = The final answer: (D).
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