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Manager
Joined: 12 Sep 2006
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Train T leaves from town A for town B and travels at a [#permalink]
 12 Sep 2006, 06:09
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Train T leaves from town A for town B and travels at a constant speed of Xmph. Train S leaves town B for town A, later than train T, and also travels at a constant speed of Y mph. Will they meet closer to town A of town B?
1- y > x
2- They finished their trips at the same time
The correct answer is B, but can someone provide a valid explanation?
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Intern
Joined: 04 May 2006
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1 y>x tells us nothing, because we have no idea which train gets there first. not sufficient.
2 tells us everything, becuase if we know that the second train leaves after the first, and they get to their destinations at the same time then the first train must have reached the midpoint first (if it didnt then they would not reach the other end at the same time). So they must cross paths closer to the second trains point of origin. So this is sufficient.
I didnt use any formulas here, just intuition.
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Manager
Joined: 12 Sep 2006
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but what if the second train travels at a faster speed?
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VP
Joined: 25 Jun 2006
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B.
2) means B definitely travels faster than T.
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