Two trains are traveling on parallel tracks in the same direction. The faster train travels at 110 miles per hour, while the slower train travels at 100 miles per hour. At 1 o’clock the faster train is 40 miles behind the slower one. How far apart are the two trains at 7 o'clock?\nOptions:\n(A) 20 miles\n(B) 80 miles\n(C) 90 miles\n(D) 120 miles\n(E) 400 miles Let's think first. Stream of consciousness:
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Answer = A. 20 miles\nRelational speed = 110 - 100 = 10 miles per hour\nIn 6 hours, difference = 10 * 6 = 60 miles\nFast train trailing 40 miles, so effective difference = 60 - 40 = 20 miles
So, the answer is (A).
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