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

It is currently 17 Apr 2014, 08:02

STARTING SHORTLY:

Dealing with a Ding - Webinar by GMATClub and Admissionado Consulting.


Close

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
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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Train A traveling at 60 m/hr leaves New York for Dallas at 6

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
5 KUDOS received
Moderator
Moderator
User avatar
Joined: 01 Sep 2010
Posts: 2173
Followers: 171

Kudos [?]: 1512 [5] , given: 610

GMAT Tests User Premium Member
Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 31 Oct 2012, 03:26
5
This post received
KUDOS
Expert's post
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

68% (03:21) correct 31% (02:31) wrong based on 261 sessions
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
[Reveal] Spoiler: OA

_________________

KUDOS is the good manner to help the entire community.

18 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 17298
Followers: 2870

Kudos [?]: 18359 [18] , given: 2347

GMAT Tests User CAT Tests
Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 31 Oct 2012, 03:37
18
This post received
KUDOS
Expert's post
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.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

1 KUDOS received
Moderator
Moderator
User avatar
Joined: 01 Sep 2010
Posts: 2173
Followers: 171

Kudos [?]: 1512 [1] , given: 610

GMAT Tests User Premium Member
Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 31 Oct 2012, 04:00
1
This post received
KUDOS
Expert's post
Thank you Sir. This was tough but relative speed as I can see, often, is the key :)
_________________

KUDOS is the good manner to help the entire community.

5 KUDOS received
Intern
Intern
Joined: 18 Oct 2012
Posts: 4
Followers: 0

Kudos [?]: 8 [5] , given: 9

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 31 Oct 2012, 18:12
5
This post received
KUDOS
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
Senior Manager
Senior Manager
User avatar
Joined: 13 Aug 2012
Posts: 465
Concentration: Marketing, Finance
GMAT 1: Q V0
GPA: 3.23
Followers: 14

Kudos [?]: 151 [0], given: 11

GMAT ToolKit User GMAT Tests User
Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 03 Dec 2012, 00:48
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

AnsweR: C
_________________

Impossible is nothing to God.

Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 17298
Followers: 2870

Kudos [?]: 18359 [0], given: 2347

GMAT Tests User CAT Tests
Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 12 Aug 2013, 02:22
Expert's post
Senior Manager
Senior Manager
Joined: 10 Jul 2013
Posts: 344
Followers: 2

Kudos [?]: 79 [0], given: 102

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 12 Aug 2013, 05:19
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
_________________

Asif vai.....

Senior Manager
Senior Manager
User avatar
Joined: 13 May 2013
Posts: 476
Followers: 0

Kudos [?]: 35 [0], given: 134

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 13 Aug 2013, 11:36
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.

ANSWER: C. 120 m/hr
Senior Manager
Senior Manager
User avatar
Joined: 23 Oct 2010
Posts: 380
Location: Azerbaijan
Concentration: Finance
GMAT 1: 690 Q47 V38
Followers: 11

Kudos [?]: 111 [0], given: 72

GMAT ToolKit User
Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 20 Nov 2013, 09:26
In 3 hours A travels 60*3=180km
Train B needs 6 hours to catch A 180/(90-60)=6hours

Trains b and c will meet (90+x)*6=1260.
X=120
_________________

Happy are those who dream dreams and are ready to pay the price to make them come true

VP
VP
User avatar
Status: I'm back and not stopping until I hit 760+
Joined: 06 Sep 2013
Posts: 1329
Location: United States
Concentration: Finance, General Management
Schools: Wharton '17
GPA: 3.5
WE: Corporate Finance (Investment Banking)
Followers: 7

Kudos [?]: 86 [0], given: 170

GMAT ToolKit User CAT Tests
Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 31 Dec 2013, 13:17
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

Cheers!
J :)
Intern
Intern
Joined: 13 Dec 2013
Posts: 6
Followers: 0

Kudos [?]: 2 [0], given: 26

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 07 Jan 2014, 18:38
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,
1 KUDOS received
Veritas Prep GMAT Instructor
User avatar
Joined: 16 Oct 2010
Posts: 4171
Location: Pune, India
Followers: 894

Kudos [?]: 3787 [1] , given: 148

Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 07 Jan 2014, 19:13
1
This post received
KUDOS
Expert's post
guimooow wrote:
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.
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Save $100 on Veritas Prep GMAT Courses And Admissions Consulting
Enroll now. Pay later. Take advantage of Veritas Prep's flexible payment plan options.

Veritas Prep Reviews

Intern
Intern
Joined: 19 Nov 2012
Posts: 34
Followers: 0

Kudos [?]: 6 [0], given: 3

CAT Tests
Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 04 Feb 2014, 16:42
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.
VP
VP
User avatar
Status: I'm back and not stopping until I hit 760+
Joined: 06 Sep 2013
Posts: 1329
Location: United States
Concentration: Finance, General Management
Schools: Wharton '17
GPA: 3.5
WE: Corporate Finance (Investment Banking)
Followers: 7

Kudos [?]: 86 [0], given: 170

GMAT ToolKit User CAT Tests
Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6 [#permalink] New post 04 Feb 2014, 17:13
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.

Cheers
J

Posted from my mobile device Image
Re: Train A traveling at 60 m/hr leaves New York for Dallas at 6   [#permalink] 04 Feb 2014, 17:13
    Similar topics Author Replies Last post
Similar
Topics:
New posts 3 Experts publish their posts in the topic A train travels from New York to Chicago, a distance of becoolja 4 15 Jul 2004, 09:41
New posts Train A leaves New York for Boston at 3 PM and travels at kevincan 1 15 Sep 2006, 12:51
Popular new posts 8 Experts publish their posts in the topic Train A leaves New York for Boston at 3 PM and travels at johnycute 15 30 May 2007, 20:16
Popular new posts 42 Experts publish their posts in the topic Train A leaves New York for Boston at 3 PM and travels at rohitgoel15 28 21 Jul 2010, 23:49
New posts 3 Experts publish their posts in the topic Train A leaves New York at 9am Eastern Time on Monday Manaswita 3 10 Sep 2013, 04:39
Display posts from previous: Sort by

Train A traveling at 60 m/hr leaves New York for Dallas at 6

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.