In a relay race tournament, teams of three runners each cover a total distance of 12 miles. The first runner runs at a speed of 4 miles per hour, the second runner at 6 miles per hour, and the third runner at 8 miles per hour. Assuming there are no breaks between the runners, how long does it take for the team to complete the entire distance? Let's think step by step and output the final answer within \boxed{}.
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