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 Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

31 Oct 2012, 04:26

12

This post received KUDOS

33

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

55% (hard)

Question Stats:

69% (02:37) correct
31% (02:36) wrong based on 717 sessions

HideShow timer Statistics

Train A traveling at 60 m/hr leaves New York for Dallas at 6 P.M. Train B traveling at 90 m/hr also leaves New York for Dallas at 9 P.M. Train C leaves Dallas for New York at 9 P.M. If all three trains meet at the same time between New York and Dallas, what is the speed of Train C if the distance between Dallas and New York is 1260 miles?

A. 60 m/hr B. 90 m/hr C. 120 m/hr D. 135 m/hr E. 180 m/hr

Train A traveling at 60 m/hr leaves New York for Dallas at 6 P.M. Train B traveling at 90 m/hr also leaves New York for Dallas at 9 P.M. Train C leaves Dallas for New York at 9 P.M. If all three trains meet at the same time between New York and Dallas, what is the speed of Train C if the distance between Dallas and New York is 1260 miles?

A. 60 m/hr B. 90 m/hr C. 120 m/hr D. 135 m/hr E. 180 m/hr

Relative speed of train A and train B is 90-60=30 miles per hour, thus B will gain 30 miles every hour compared to A.

Now, in 3 hours (from 6 P.M. to 9 P.M.) that A traveled alone, it covered 60*3=180 miles. To catch up A (to meet A), B will need 180/30=6 hours.

Next, in 6 hours B will cover 6*90=540 miles to the meeting point, thus C covered 1260-540=720 miles.

Since C also needed 6 hours to meet A and B (C also left at 9 P.M), then its rate is 720/6=120 miles per hour.

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

31 Oct 2012, 19:12

8

This post received KUDOS

1

This post was BOOKMARKED

Let the time be t for the train (B) traveling at 90 miles/hr So the speed of train (A) traveling at 60 miles/hr will be t+3 (as it started 3 hours before train B)

So using the formula r x t = d Train B --------- 90 x t = 90t (1) Train A --------- 60 x (t+3) = 60t + 180 (2) They are traveling in the same direction. 90t = 60t + 180 30t = 180 t = 6

In 6 hours train A and train B will travel a distance of 540 miles. Train C is running in opposite direction. Total distance is 1260 miles so out of the total distance 540 miles is covered by the two trains so train C has to cover 1260 - 540 miles = 720 miles In order to cover 720 miles in 6 hours train C has to run at the speed of 720/6 = 120 miles/hr

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

03 Dec 2012, 01:48

2

This post received KUDOS

Train A and Train B meets somewhere between NY and Dallas. This means the miles covered by Train A and Train B were equal during that point. Also, we know that Train A travelled for 3 hours before Train B started.

Distance of Train A + Distance of Train A before Train B starts = Distance of Train B

\(60t + 60(3) = 90t\) \(t = 6 hrs\)

Train B has covered 90 x 6 = 540 miles when it was met by Train C (which covered the rest of the tracks between Dallas and NY) 1260 - 540 = 720 miles

Train C also started the same time as B. \(R = 720/6 = 120 mph\)

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

12 Aug 2013, 06:19

carcass wrote:

Train A traveling at 60 m/hr leaves New York for Dallas at 6 P.M. Train B traveling at 90 m/hr also leaves New York for Dallas at 9 P.M. Train C leaves Dallas for New York at 9 P.M. If all three trains meet at the same time between New York and Dallas, what is the speed of Train C if the distance between Dallas and New York is 1260 miles?

A. 60 m/hr B. 90 m/hr C. 120 m/hr D. 135 m/hr E. 180 m/hr

.. (A) s=60t (B) s = 90(t-3) (C) 1260-s=V(t-3) from these t=9, s=540 and velocity of C = 120
_________________

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

13 Aug 2013, 12:36

Train A traveling at 60 m/hr leaves New York for Dallas at 6 P.M. Train B traveling at 90 m/hr also leaves New York for Dallas at 9 P.M. Train C leaves Dallas for New York at 9 P.M. If all three trains meet at the same time between New York and Dallas, what is the speed of Train C if the distance between Dallas and New York is 1260 miles?

All three trains meet at the same time. If we can find how many miles it takes for the faster train B to catch up to the slower train A, we can figure out at what time all three trains meet.

Train B gains 30miles per hour on train B every hour it travels (90mi/hr - 60 mi/hr = 30 mi/hr) Therefore, if B started when A was 180 mi ahead, it will need 180/30 = 6 hours to catch up to A.

In the 6 hours it takes for train B to catch up to A, it travels 6+90 = 540 miles. Therefore, when A,B and C meet C has traveled 1260-540 = 720 miles. If train C left at 9PM and it took 6 hours for A to catch up to B (and meet C) then the speed of C is d/t ===> 720/6 = 120 mi/hour.

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

31 Dec 2013, 14:17

carcass wrote:

Train A traveling at 60 m/hr leaves New York for Dallas at 6 P.M. Train B traveling at 90 m/hr also leaves New York for Dallas at 9 P.M. Train C leaves Dallas for New York at 9 P.M. If all three trains meet at the same time between New York and Dallas, what is the speed of Train C if the distance between Dallas and New York is 1260 miles?

A. 60 m/hr B. 90 m/hr C. 120 m/hr D. 135 m/hr E. 180 m/hr

Got it

First since A starts 3 hours before it travels 180 miles in that time span

Now, B needs to catch up first so it will need (30)(t) = 180 ---> 6 hours to do so

In 6 hours, B will travel 540 miles

Now, C needs to meet them at the same time

So in 6 hours it will need to cover 1260 - 540 = 720 miles

720 / 6= 120 miles/hour

Hence C is the answer

Provide kudos if you think that this post was helpful

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

07 Jan 2014, 19:38

1

This post received KUDOS

I understand how the problem is solved but my doubt is: why do they meet at that determinate point with C (720 miles). Why not later? there is no equation that relates the first two trains with the C.

I understand how the problem is solved but my doubt is: why do they meet at that determinate point with C (720 miles). Why not later? there is no equation that relates the first two trains with the C.

Thank you in advance,

It is given to you in the question, we are not assuming it: "If all three trains meet at the same time between New York and Dallas," This is important data that the question stem gives us. It tells us that their speeds are related in a way that all three trains meet together - just when B crosses A, C also passes A and B.
_________________

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

04 Feb 2014, 17:42

A a question for all,

Do RTD PS questions such as this often take you well over 2 minutes? I find it often takes me a minute to read the question - then re-read to write down all the pertinent information. I often need another 2 minutes to complete all of the calculations. Just wondering if it's just me, or if others are in the same boat.

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

04 Feb 2014, 18:13

Well I can only speak for myself but short answer is no, it doesn't at least its a very complex RTD question such as the one with roses for example. But like everything its just practice and its good that you read carefully cause thats the most important thing in RTD.

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

02 May 2015, 11:40

Bunuel wrote:

carcass wrote:

Train A traveling at 60 m/hr leaves New York for Dallas at 6 P.M. Train B traveling at 90 m/hr also leaves New York for Dallas at 9 P.M. Train C leaves Dallas for New York at 9 P.M. If all three trains meet at the same time between New York and Dallas, what is the speed of Train C if the distance between Dallas and New York is 1260 miles?

A. 60 m/hr B. 90 m/hr C. 120 m/hr D. 135 m/hr E. 180 m/hr

Relative speed of train A and train B is 90-60=30 miles per hour, thus B will gain 30 miles every hour compared to A.

Now, in 3 hours (from 6 P.M. to 9 P.M.) that A traveled alone, it covered 60*3=180 miles. To catch up A (to meet A), B will need 180/30=6 hours.

Next, in 6 hours B will cover 6*90=540 miles to the meeting point, thus C covered 1260-540=720 miles.

Since C also needed 6 hours to meet A and B (C also left at 9 P.M), then its rate is 720/6=120 miles per hour.

Answer: C.

Hope it's clear.

Can you please explain : To catch up A (to meet A), B will need 180/30=6 hours

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

03 May 2015, 06:59

carcass wrote:

Train A traveling at 60 m/hr leaves New York for Dallas at 6 P.M. Train B traveling at 90 m/hr also leaves New York for Dallas at 9 P.M. Train C leaves Dallas for New York at 9 P.M. If all three trains meet at the same time between New York and Dallas, what is the speed of Train C if the distance between Dallas and New York is 1260 miles?

A. 60 m/hr B. 90 m/hr C. 120 m/hr D. 135 m/hr E. 180 m/hr

Train A has already taken 3hrs when train B started , lets make a equation of distance .

\(180 + 60*T_A = 90*T_B\)

\(6 + 2*T_A = 3*T_B\)

since \(T_A = T_B\) so , \(T_A=T_B=6hrs.\) Distance travelled by B in 6hrs = 90*6 = 540 Net time taken by A = 6+3= 9 hrs. (just for information)

Let C be speed of train C , then

\(\frac{1260-90*6}{C} = 6\)

C= 120 Answer.
_________________

Thanks, Lucky

_______________________________________________________ Kindly press the to appreciate my post !!

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

03 May 2015, 07:30

A gets a head start of 60*3= 180 miles. B closes in on A with 30 miles/hour. He will catch up with A in 180/30=6 hours. At that time A has travelled 60*(6+3)=540 miles. This means that C has travelled 1260-540=720 miles in 6 hours. 720/60=120. Hence, C should be correct.
_________________

I love being wrong. An incorrect answer offers an extraordinary opportunity to improve.

Train A traveling at 60 m/hr leaves New York for Dallas at 6 P.M. Train B traveling at 90 m/hr also leaves New York for Dallas at 9 P.M. Train C leaves Dallas for New York at 9 P.M. If all three trains meet at the same time between New York and Dallas, what is the speed of Train C if the distance between Dallas and New York is 1260 miles?

A. 60 m/hr B. 90 m/hr C. 120 m/hr D. 135 m/hr E. 180 m/hr

Relative speed of train A and train B is 90-60=30 miles per hour, thus B will gain 30 miles every hour compared to A.

Now, in 3 hours (from 6 P.M. to 9 P.M.) that A traveled alone, it covered 60*3=180 miles. To catch up A (to meet A), B will need 180/30=6 hours.

Next, in 6 hours B will cover 6*90=540 miles to the meeting point, thus C covered 1260-540=720 miles.

Since C also needed 6 hours to meet A and B (C also left at 9 P.M), then its rate is 720/6=120 miles per hour.

Answer: C.

Hope it's clear.

Can you please explain : To catch up A (to meet A), B will need 180/30=6 hours

The question uses the concept of relative speed. Let me explain it you its working.

Refer the following diagram for this question:

The diagram shows the relative positioning of trains at 9 PM. Trains B & C are starting from NY & Dallas respectively while train A is at a distance of 180 miles from NY ( as train A started from NY at a speed of 60 miles/hr 3 hours before at 6 PM. SO distance traveled by train A = 60 * 3 = 180 miles)

Since all the trains meet at the same point, it would be enough if we found out meeting point of trains A & B. Train A is 180 miles ahead of train B at 9 PM and the difference between the speeds of trains A & B is 30 miles/hr (Train B travels at a speed of 90 miles/hr and train A travels at a speed of 60 miles/hr).

Using the formula forDistance = Speed * Time, we can say that 180 = 30 * t i.e. t= 6 hours. This means that train B and A will meet 6 hours after 9 PM. In other words, train B will catch up with train A after 6 hours.

So, distance travelled by train B in 6 hours = 90 * 6 = 540 miles. Thus train C will need to travel 1260 - 540 = 720 miles in 6 hours. So, speed of train C would be \(\frac{720}{6} = 120\) miles/hour

In Distance & Speed question which involves concept of relative speed, it is always helpful to draw a diagram and visualize the solution.

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink]

Show Tags

09 Jul 2017, 15:35

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.
_________________

Version 8.1 of the WordPress for Android app is now available, with some great enhancements to publishing: background media uploading. Adding images to a post or page? Now...

Post today is short and sweet for my MBA batchmates! We survived Foundations term, and tomorrow's the start of our Term 1! I'm sharing my pre-MBA notes...

“Keep your head down, and work hard. Don’t attract any attention. You should be grateful to be here.” Why do we keep quiet? Being an immigrant is a constant...