Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 26 Jul 2016, 00:10

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Train X departs Rockburg for Williamsland at 1:00 p.m. and

Author Message
TAGS:

### Hide Tags

Intern
Joined: 11 Sep 2011
Posts: 6
Followers: 0

Kudos [?]: 7 [0], given: 0

Train X departs Rockburg for Williamsland at 1:00 p.m. and [#permalink]

### Show Tags

10 Oct 2012, 04:04
2
This post was
BOOKMARKED
00:00

Difficulty:

55% (hard)

Question Stats:

63% (02:30) correct 37% (01:02) wrong based on 156 sessions

### HideShow timer Statistics

Train X departs Rockburg for Williamsland at 1:00 p.m. and train Y departs Williamsland for Rockburg at 2:00 p.m. If Rockburg and Williamsland are 200 miles apart, how much faster is train X than train Y ?

(1) Train X arrives at Williamsland at 5:00 p.m.
(2) Train X and train Y pass each other at 3:30 p.m.

[Reveal] Spoiler:
This is what I did

Statement 1 can give us the rate for train x which is 200/4=50, so its not sufficient.

Statement 2 is not sufficient beccause it doesn't give a clue about either rates, Not sufficient.

I realize its C, but in order to use it I think the equation should be like this:

2.5*50= 3/2*Ry
I just need the confirmation whether my construction for the equation from statements 1 and 2 is right , because I saw an OA stating that the equation constructed from both A and B would be:

(2.5 hours)(50 mph)+ (1.5 hours)(Y’s rate) = 200 miles

I don't understand where that equation came from since the meeting distance when train x and y pass by each other is not 200 miles yet, so how is the equation above was constructed???

I would appreciate it if I can get some hint about the right equation from A and B

Thank you very much
[Reveal] Spoiler: OA
Senior Manager
Joined: 28 Jun 2009
Posts: 454
Location: United States (MA)
Followers: 18

Kudos [?]: 147 [0], given: 46

Re: Train X departs Rockburg for Williamsland at 1:00 p.m. and [#permalink]

### Show Tags

10 Oct 2012, 09:13
Asked : how much faster is train X than train Y ?

say X's speed is X and Y's speed is Y
We need to find speeds of both trains OR difference between speeds OR X-Y

(1) Train X arrives at Williamsland at 5:00 p.m.

So X travels 200 miles in 4 hours (1 PM to 5PM)
X's speed : 50 mph

Can't get Y's speed from statemet (1) - Insufficient.

(2) Train X and train Y pass each other at 3:30 p.m.

At 3:30 pm,
X has travelled for 2.5 hours
Y has travelled for 1.5 hours

when they cross each other, they both have completed 200 miles together.

2.5X + 1.5Y = 200

we can not get X-Y from this
statemet (2) - Insufficient.

combining

X : 50 mph -> from statemet (1)
2.5X + 1.5Y = 200 -> statemet (2)

We can get Y's value and X-Y.

Together they are sufficient.

Hence C.
Director
Joined: 22 Mar 2011
Posts: 612
WE: Science (Education)
Followers: 90

Kudos [?]: 804 [0], given: 43

Re: Train X departs Rockburg for Williamsland at 1:00 p.m. and [#permalink]

### Show Tags

10 Oct 2012, 10:24
Train X departs Rockburg for Williamsland at 1:00 p.m. and train Y departs Williamsland for Rockburg at 2:00 p.m. If Rockburg and Williamsland are 200 miles apart, how much faster is train X than train Y ?

(1) Train X arrives at Williamsland at 5:00 p.m.
(2) Train X and train Y pass each other at 3:30 p.m.

[Reveal] Spoiler:
This is what I did

Statement 1 can give us the rate for train x which is 200/4=50, so its not sufficient.

Statement 2 is not sufficient beccause it doesn't give a clue about either rates, Not sufficient.

I realize its C, but in order to use it I think the equation should be like this:

2.5*50= 3/2*Ry
I just need the confirmation whether my construction for the equation from statements 1 and 2 is right , because I saw an OA stating that the equation constructed from both A and B would be:

(2.5 hours)(50 mph)+ (1.5 hours)(Y’s rate) = 200 miles

I don't understand where that equation came from since the meeting distance when train x and y pass by each other is not 200 miles yet, so how is the equation above was constructed???

I would appreciate it if I can get some hint about the right equation from A and B

Thank you very much

(1) Not sufficient, as we can only deduce the speed of train X. We have no information on train Y.

(2) Now we know that until they pass each other, the two trains traveled 2.5 and 2.5 hours, respectively.
Again not sufficient. Either train can be faster than the other one, we just know for how long each traveled.

(1) and (2): sufficient, as we have now the speed of train X, the time it travelled, so we can find where did they meet (distance covered by each one), so we can find Y's speed and we can compare the two speeds. Of course, sufficient, and no need to compute anything.

_________________

PhD in Applied Mathematics
Love GMAT Quant questions and running.

Last edited by EvaJager on 11 Oct 2012, 02:27, edited 1 time in total.
Intern
Joined: 11 Sep 2011
Posts: 6
Followers: 0

Kudos [?]: 7 [0], given: 0

Re: Train X departs Rockburg for Williamsland at 1:00 p.m. and [#permalink]

### Show Tags

11 Oct 2012, 00:04
piyatiwari wrote:
Asked : how much faster is train X than train Y ?

say X's speed is X and Y's speed is Y
We need to find speeds of both trains OR difference between speeds OR X-Y

(1) Train X arrives at Williamsland at 5:00 p.m.

So X travels 200 miles in 4 hours (1 PM to 5PM)
X's speed : 50 mph

Can't get Y's speed from statemet (1) - Insufficient.

(2) Train X and train Y pass each other at 3:30 p.m.

At 3:30 pm,
X has travelled for 2.5 hours
Y has travelled for 1.5 hours

when they cross each other, they both have completed 200 miles together.

2.5X + 1.5Y = 200

we can not get X-Y from this
statemet (2) - Insufficient.

combining

X : 50 mph -> from statemet (1)
2.5X + 1.5Y = 200 -> statemet (2)

We can get Y's value and X-Y.

Together they are sufficient.

Hence C.

Thank you for your explain, actually I was wondering about the extracted equation from the two statements, I didn't get why when they cross each other, they both have completed 200 miles together??

shouldn't the equation be like this

2.5*50 = 1.5y------ because when they cross each other, then they both will have the same distance, but it also means that they didn't complete the whole distance, which is 200
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 6747
Location: Pune, India
Followers: 1874

Kudos [?]: 11527 [0], given: 219

Re: Train X departs Rockburg for Williamsland at 1:00 p.m. and [#permalink]

### Show Tags

11 Oct 2012, 01:06
Expert's post
piyatiwari wrote:
Asked : how much faster is train X than train Y ?

say X's speed is X and Y's speed is Y
We need to find speeds of both trains OR difference between speeds OR X-Y

(1) Train X arrives at Williamsland at 5:00 p.m.

So X travels 200 miles in 4 hours (1 PM to 5PM)
X's speed : 50 mph

Can't get Y's speed from statemet (1) - Insufficient.

(2) Train X and train Y pass each other at 3:30 p.m.

At 3:30 pm,
X has travelled for 2.5 hours
Y has travelled for 1.5 hours

when they cross each other, they both have completed 200 miles together.

2.5X + 1.5Y = 200

we can not get X-Y from this
statemet (2) - Insufficient.

combining

X : 50 mph -> from statemet (1)
2.5X + 1.5Y = 200 -> statemet (2)

We can get Y's value and X-Y.

Together they are sufficient.

Hence C.

Thank you for your explain, actually I was wondering about the extracted equation from the two statements, I didn't get why when they cross each other, they both have completed 200 miles together??

shouldn't the equation be like this

2.5*50 = 1.5y------ because when they cross each other, then they both will have the same distance, but it also means that they didn't complete the whole distance, which is 200

X started out from R and Y started out from W. The distance between R and W is 200 miles. They met each other at 3:30. HOw much distance do they need to cover together to meet? They need to cover the original distance between them. What is the original distance between them? 200 miles. So they together covered 200 miles. That's how you get the equation.

Distance covered by X + Distance covered by Y = 200
(time of X * speed of X) + (time of Y * speed of Y) = 200
2.5*50 + 1.5 * Y = 200

Think, if you are your friend are 10 m apart and you want to meet, how many meters do you need to cover together? 10 M of course. It doesn't matter whether you cover 9 and he covers 1 or you cover 2 and he covers 8 etc. But together, you need to cover 10. It is not essential that you both need to cover equal distances. If you start at different times and/or if your speed is different, you will likely cover different distances. This is the same case.

You can actually do this equation using a diagram and without making any equation. I will explain it in a while.
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199 Veritas Prep Reviews Veritas Prep GMAT Instructor Joined: 16 Oct 2010 Posts: 6747 Location: Pune, India Followers: 1874 Kudos [?]: 11527 [0], given: 219 Re: Train X departs Rockburg for Williamsland at 1:00 p.m. and [#permalink] ### Show Tags 11 Oct 2012, 02:34 Expert's post madimo wrote: Train X departs Rockburg for Williamsland at 1:00 p.m. and train Y departs Williamsland for Rockburg at 2:00 p.m. If Rockburg and Williamsland are 200 miles apart, how much faster is train X than train Y ? (1) Train X arrives at Williamsland at 5:00 p.m. (2) Train X and train Y pass each other at 3:30 p.m. This is what we know: Distance between X and Y initially is 200 miles. X starts at 1:00 pm and Y at 2:00 pm. We need to know the difference between speeds of X and Y. (1) Train X arrives at Williamsland at 5:00 p.m. We know the time taken by X to cover 200 miles but not the time taken by Y. So we cannot say what the difference between their speeds is. (2) Train X and train Y pass each other at 3:30 p.m. The two trains cross each other at 3:30. So X has traveled for 2.5 hrs and Y for 1.5 hrs and they have together covered 200 miles. But we don't know the individual distances covered by them and hence, we don't know their speeds. Think of it this way: say X is very slow. It could still start at 1:00 and meet at 3:30 if Y is very fast. On the other hand, if X is very fast, it could start at 1:00, meet at 3:30 (Y is slow) and reach the other side. Now the problem is to figure out if together the two statements are sufficient. Note that they meet at 3:30 and X reaches the other side at 5:00 i.e. it takes 1.5 hrs to cover the remaining distance. This 'remaining distance' is the distance covered by Y when it started at 2:00 and met at 3:30 i.e. in 1.5 hrs. Basically, V=X and Y both covered the same distance in 1.5 hrs and hence their speeds are the same. So X has the same speed as Y. I have made a diagram below to reinforce this. Attachment: Ques3.jpg [ 8.4 KiB | Viewed 2001 times ] Notice that Y travels on the green line and takes 1.5 hrs to do it. X travels from the meeting point to the other end (same as the distance of the green line) in 1.5 hrs. SO we can conclude that their speeds are the same. _________________ Karishma Veritas Prep | GMAT Instructor My Blog Get started with Veritas Prep GMAT On Demand for$199

Veritas Prep Reviews

Intern
Joined: 11 Sep 2011
Posts: 6
Followers: 0

Kudos [?]: 7 [0], given: 0

Re: Train X departs Rockburg for Williamsland at 1:00 p.m. and [#permalink]

### Show Tags

11 Oct 2012, 03:00
Thank you very much guys you made it clear to me now, cheers
Senior Manager
Joined: 13 May 2013
Posts: 472
Followers: 3

Kudos [?]: 136 [1] , given: 134

Re: Train X departs Rockburg for Williamsland at 1:00 p.m. and [#permalink]

### Show Tags

01 Aug 2013, 13:25
1
KUDOS
Train X departs R for W at 1:00 p.m. and train Y departs W for R at 2:00 p.m. If R and W are 200 miles apart, how much faster is train X than train Y ?
We are looking for the speed of train X vs. train Y.

Speed = distance/time
Distance = rate*time

(1) Train X arrives at Williamsland at 5:00 p.m.
This tells us that train X traveled for four hours. The average speed of X is therefore 50 miles/hour. Still, we know nothing about the speed of Y.
INSUFFICIENT

(2) Train X and train Y pass each other at 3:30 p.m.
Depending on the speed of X and Y, they could have passed one another at the midpoint or at some other point along the tracks. We know nothing of their speed.
INSUFFICIENT

Train X travels 2.5 hours and train Y travels 1.5 hours when they pass each other. When they do pass one another, they will have covered a total of 200 miles.
d1+d2=200
distance = r*t
d1: (50mph*2.5 hours)
d2: (s*1.5 hours+
total distance = 200
(50*2.5)+(s*1.5)=200
125+1.5s = 200
1.5s = 75
s = 50

The speed for both trains is the same, 50 miles/hour.
SUFFICIENT

(C)
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 10597
Followers: 495

Kudos [?]: 129 [0], given: 0

Re: Train X departs Rockburg for Williamsland at 1:00 p.m. and [#permalink]

### Show Tags

25 Jun 2015, 08:16
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: Train X departs Rockburg for Williamsland at 1:00 p.m. and   [#permalink] 25 Jun 2015, 08:16
Similar topics Replies Last post
Similar
Topics:
1 Did a train arrive at station X no earlier than 4:00 p.m. and no later 1 05 Jun 2016, 14:27
6 Superfast train A leaves Newcastle for Birmingham at 3 PM and travels 4 06 Apr 2015, 07:46
20 Allison always leaves her office at 5.00pm and reaches her 3 03 Jun 2014, 06:08
384 Train A leaves New York for Boston at 3 PM and travels at 50 22 Jul 2010, 00:49
14 Train A leaves New York for Boston at 3 PM and travels at 17 30 May 2007, 21:16
Display posts from previous: Sort by