Late Train
Two trains, A and B, leave their respective starting points at the same time and travel in opposite directions. They travel at constant speeds, and pass at point M. One travels at twice the speed of the other. If one of the trains leaves five minutes late they pass at a point 2 miles from point M. What is the speed of the slow train, in miles per hour?
The answer is 36.
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1 solution
Let's say A is the faster 🚆 with speed 2v and B with speed v. M & A's starting point would be twice the distance compared to M & B's starting point, so MA = 2d and MB = d.
2vt = 2d + 2
vt = d + 1 v(t – 1/12) = d – 2
v/12 = 3
v = 36 mph
OR
2v(t – 1/12) = 2d – 2
vt – v/12 = d – 1 vt = d + 2
v/12 = 3
v = 36 mph