Question: A can do a piece of work in 4 hours; B and C together can do it in 2 hours, which A and C together can do it in 2 hours. How long will B alone take to do it?\nOptions:\n(A) 2hours\n(B) 3hours\n(C) 4hours\n(D) 5hours\n(E) 6hours Let's think first. Some random reasoning:
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A's 1 hour work = 1/4;\n(B + C)'s 1 hour work = 1/2;\n(A + C)'s 1 hour work = 1/2\n(A + B + C)'s 1 hour work = (1/4 + 1/2) = 3/4\nB's 1 hour work = (3/4 - 1/2) = 1/4\nB alone will take 4 hours to do the work. The final answer: (C).
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