A water tank has a capacity of 1000 liters. It is being filled by three pipes: Pipe A, Pipe B, and Pipe C. Pipe A can fill the tank at a rate of 10 liters per minute, Pipe B at a rate of 15 liters per minute, and Pipe C at a rate of 25 liters per minute. How long will it take to fill the tank if all three pipes are opened at the same time? Let's think step by step and output the final answer within \boxed{}.
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