Trains A and B travel at the same constant rate in opposite directions along the same route between Town G and Town H. If, after traveling for 2 hours, Train A passes Train B, how long does it take Train B to travel the entire distance between Town G and Town H?
(1) Train B started traveling between Town G and Town H 1 hour after Train A started traveling between Town H and Town G.
(2) Train B travels at the rate of 150 miles per hour.
Trains A and B - MGMAT
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Here's the key piece of info in the stem (which I missed at first too!):pkw209 wrote:Trains A and B travel at the same constant rate in opposite directions along the same route between Town G and Town H. If, after traveling for 2 hours, Train A passes Train B, how long does it take Train B to travel the entire distance between Town G and Town H?
(1) Train B started traveling between Town G and Town H 1 hour after Train A started traveling between Town H and Town G.
(2) Train B travels at the rate of 150 miles per hour.
Trains A and B travel at the same constant rate...
So, we know that rate(a) = rate(b). We also know that they meet 2 hours after A starts.
From (2) we have rate(b) but no info about distance.. insufficient.
From (1) we know that A traveled 1 hour longer than B when they met. Since A has been traveling for 2 hours, B must have been traveling for 1 hour.
Well, A and B travel at the same rate. Since it took a combined 3 hours of work to meet (2 hours by A, 1 hour by B), it would also take either train 3 hours of alone time to make the full journey: 1 is sufficient alone, choose (A).
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The official answer is A. This problem is from a MGMAT CAT. Explanation is below.
(1) SUFFICIENT: This tells us that B started traveling 1 hour after Train A started traveling. From the question we know that Train A had been traveling for 2 hours when the trains passed each other. Thus, train B, which started 1 hour later, must have been traveling for 2 - 1 = 1 hour when the trains passed each other.
Let's call the point at which the two trains pass each other Point P. Train A travels from Town H to Point P in 2 hours, while Train B travels from Town G to Point P in 1 hour. Adding up these distances and times, we have it that the two trains covered the entire distance between the towns in 3 (i.e. 2 + 1) hours of combined travel time. Since both trains travel at the same rate, it will take 3 hours for either train to cover the entire distance alone. Thus, from Statement (1) we know that it will take Train B 3 hours to travel between Town G and Town H.
(1) SUFFICIENT: This tells us that B started traveling 1 hour after Train A started traveling. From the question we know that Train A had been traveling for 2 hours when the trains passed each other. Thus, train B, which started 1 hour later, must have been traveling for 2 - 1 = 1 hour when the trains passed each other.
Let's call the point at which the two trains pass each other Point P. Train A travels from Town H to Point P in 2 hours, while Train B travels from Town G to Point P in 1 hour. Adding up these distances and times, we have it that the two trains covered the entire distance between the towns in 3 (i.e. 2 + 1) hours of combined travel time. Since both trains travel at the same rate, it will take 3 hours for either train to cover the entire distance alone. Thus, from Statement (1) we know that it will take Train B 3 hours to travel between Town G and Town H.
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That's what I said!pkw209 wrote:The official answer is A. This problem is from a MGMAT CAT. Explanation is below.
(1) SUFFICIENT: This tells us that B started traveling 1 hour after Train A started traveling. From the question we know that Train A had been traveling for 2 hours when the trains passed each other. Thus, train B, which started 1 hour later, must have been traveling for 2 - 1 = 1 hour when the trains passed each other.
Let's call the point at which the two trains pass each other Point P. Train A travels from Town H to Point P in 2 hours, while Train B travels from Town G to Point P in 1 hour. Adding up these distances and times, we have it that the two trains covered the entire distance between the towns in 3 (i.e. 2 + 1) hours of combined travel time. Since both trains travel at the same rate, it will take 3 hours for either train to cover the entire distance alone. Thus, from Statement (1) we know that it will take Train B 3 hours to travel between Town G and Town H.
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Yes Stuart ! .. exactly your words ... they've copied you ...Stuart Kovinsky wrote:That's what I said!pkw209 wrote:The official answer is A. This problem is from a MGMAT CAT. Explanation is below.
(1) SUFFICIENT: This tells us that B started traveling 1 hour after Train A started traveling. From the question we know that Train A had been traveling for 2 hours when the trains passed each other. Thus, train B, which started 1 hour later, must have been traveling for 2 - 1 = 1 hour when the trains passed each other.
My problem I think is reading comprehension ( as strange as it may sound)
See:
a- If they travel in opposite directions, how could one pass another?
b- When they say "along the same route between Town G and Town H", does it mean from G to H? leaves G for H? both going to the same place? in opposite directions?
In your scenario, the explanation is clear, but how can I solve this kind of problems when dealing with reading-comprehension data sufficiency?
Thanks for your patience.
Silvia,