Q: Two trains are traveling on parallel tracks in the same direction. The faster train travels at 150 miles per hour, while the slower train travels at 100 miles per hour. At 2 o'clock the faster train is 10 miles behind the slower one. How far apart are the two trains at 5 o'clock?
Options:
(A) 60 miles
(B) 80 miles
(C) 90 miles
(D) 140 miles
(E) 400 miles
A: (D)
Explain how we arrive at this answer:
Explanation: Answer = D. 140 miles
Relational speed = 150 - 100 = 50 miles per hour
In 3 hours, difference = 50 * 3 = 150 miles
Fast train trailing 10 miles, so effective difference = 150 - 10 = 140 miles