GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 15 Nov 2018, 09:33

ISB R1 results on Nov 15:

Join Chat Room for Live Updates


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.

Close

Request Expert Reply

Confirm Cancel
Events & Promotions in November
PrevNext
SuMoTuWeThFrSa
28293031123
45678910
11121314151617
18192021222324
2526272829301
Open Detailed Calendar
  • Free GMAT Strategy Webinar

     November 17, 2018

     November 17, 2018

     07:00 AM PST

     09:00 AM PST

    Nov. 17, 7 AM PST. Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.
  • GMATbuster's Weekly GMAT Quant Quiz # 9

     November 17, 2018

     November 17, 2018

     09:00 AM PST

     11:00 AM PST

    Join the Quiz Saturday November 17th, 9 AM PST. The Quiz will last approximately 2 hours. Make sure you are on time or you will be at a disadvantage.

Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50610
Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train  [#permalink]

Show Tags

New post 24 Sep 2015, 21:43
1
13
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

78% (01:55) correct 22% (02:42) wrong based on 292 sessions

HideShow timer Statistics

Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train B leaves Boston at 7:45 am traveling to New York at 70 mph on a parallel track. If the distance between New York and Boston is 210 miles, at what time will the two trains pass each other?

A) 8:15 am
B) 8:45 am
C) 9:00 am
D) 9:30 am
E) Cannot be determined from the information given

Kudos for a correct solution.

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

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?
Extra-hard Quant Tests with Brilliant Analytics

Most Helpful Expert Reply
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7034
Re: Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train  [#permalink]

Show Tags

New post 25 Sep 2015, 06:54
7
2
Bunuel wrote:
Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train B leaves Boston at 7:45 am traveling to New York at 70 mph on a parallel track. If the distance between New York and Boston is 210 miles, at what time will the two trains pass each other?

A) 8:15 am
B) 8:45 am
C) 9:00 am
D) 9:30 am
E) Cannot be determined from the information given

Kudos for a correct solution.


hello,
train A will cover 60 kms in 45 min at 7:45, the time when train B starts...
distance left to cover is 210-60=150..
combined speed=80+70=150..
so the trains meet in 1 hour i.e. 7:45 + 1 hr=8:45
B
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

General Discussion
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50610
Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train  [#permalink]

Show Tags

New post 27 Sep 2015, 10:23
5
1
Bunuel wrote:
Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train B leaves Boston at 7:45 am traveling to New York at 70 mph on a parallel track. If the distance between New York and Boston is 210 miles, at what time will the two trains pass each other?

A) 8:15 am
B) 8:45 am
C) 9:00 am
D) 9:30 am
E) Cannot be determined from the information given

Kudos for a correct solution.


OFFICIAL SOLUTION:

METHOD 1: Setting Up a Multi-Part Journey Table

The “mph” tips off that this is a rates question, and the fact that the two trains are at one point traveling (or “working”) together means we are also dealing with combined rates. However, the fact that Train A travels alone for the first 45 minutes (from 7:00 am – 7:45 am) also gives this problem the characteristic of a multi-part journey question.

Now that we know we are being tested on a multi-part journey with combined rates in the second leg of the journey, we can approach strategically with a multi-part journey chart:

Image

We were given that Train A’s rate is 80mph, and we were given that Train A traveled alone for 45 minutes (0.75 of an hour). Any time you are given two parts of a three-part equation, you can solve for the third part: Train A traveled 60 miles between 7:00 am and 7:45 am.

We were also given that the total distance between the two trains is 210 miles. If we know Train A traveled alone for 60 miles, then the distance left when the trains are traveling together is 150 miles.

We are given that Train B’s rate is 80 mph. Whenever two trains are moving toward each other (or “working together”) you combine the rates: 70+80 = 150 mph. If the trains were traveling at 150mph it would have taken them 1 hour to cover the 150 miles left between them.

Starting from 7:00 am and adding on the 0.75 hours Train A traveled alone with the 1 hour the two trains traveled together, they will meet at 8:45 am. The correct answer is B.

METHOD 2: Backsolving

Perhaps you weren’t familiar or comfortable with the multi-party journey table, and you attempted to solve the problem through backsolving. Backsolving is a popular method when there are numbers in the answer choices, because the method consists of simply plugging each answer choice into the question stem and “backsolving” until you find the right one.

However, because you have to do the math for each of the answer choices, this method can often be lengthy and end up using more time than you should be on one problem – but in a bind it could have led you to the correct answer. With this method you would solve for how far each of the trains would have traveled by the given time in the answer choice, and see if their separate distances traveled, when combined, equaled a total of 210 miles.

METHOD 3: Algebra

You could have also used an algebraic set-up to solve:

Let T = the time Train A takes to get to the meeting point

210-80T = 70(T-0.75)

T = 1.75 hours

Meeting time = 7:00am + 1.75 hours = 8:45 am

As you can see, there are a multitude of approaches that will all lead you to the correct answer. If you use your practice problems as a way to explore these various methods (as opposed to simply solving with one method and moving on), you will become more and more comfortable with the question types in which each can be applied, and ultimately more successful in knowing when to use them.

Methods 1 & 2 would have been the most efficient for a question type like this, but both are equally quick and effective. Individuals’ minds all work differently, so the only way to know what works best for you is to try them all out and get as much practice as you can.

Next time you do a practice problem, go the extra mile and reflect on what choices you were faced with along the way, what decisions you made, and what methods are available that you didn’t use the first time around.

Attachment:
Screen-Shot-2013-07-30-at-1.51.34-PM.png
Screen-Shot-2013-07-30-at-1.51.34-PM.png [ 15.82 KiB | Viewed 3424 times ]

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

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?
Extra-hard Quant Tests with Brilliant Analytics

Board of Directors
User avatar
P
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4210
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User Premium Member
Re: Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train  [#permalink]

Show Tags

New post 13 Oct 2016, 07:54
Bunuel wrote:
Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train B leaves Boston at 7:45 am traveling to New York at 70 mph on a parallel track. If the distance between New York and Boston is 210 miles, at what time will the two trains pass each other?

A) 8:15 am
B) 8:45 am
C) 9:00 am
D) 9:30 am
E) Cannot be determined from the information given

Kudos for a correct solution.


Distance traveled by Train A in 45 minutes is \(\frac{45}{60}*80\) = 60 miles

Thus the distance between the Two trains gets reduced to 150 miles at 7:45 AM

Now, \(\frac{d}{80} = \frac{(150 - d)}{70}\)

So, 70d = 12000 - 80d

Or, 150d = 12000

Or, d = 80

Time taken after 7:45 AM for train A to cover distance d is - \(\frac{Distance}{Speed}\)

80/80 = 1 Hour...

So, after 1 hour from 7:45 AM the trains will meet...

Hence answer will be (B) 8:45AM

_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Manager
Manager
avatar
Joined: 29 Aug 2008
Posts: 110
Re: Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train  [#permalink]

Show Tags

New post 20 Oct 2016, 10:53
In first 45 mins Train A will cover = \(\frac{45*80}{60}\) = 60 miles

Distance b/w two trains before Train B starts = 210-60 = 150

Time in which Trains will meet =\(\frac{Distance}{Relative Speed}\) = \(\frac{150}{(80 + 70)}\) = 1 hr

Train B started at 7:45 + 1 hr = 8:45.

Option B
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2830
Re: Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train  [#permalink]

Show Tags

New post 14 Dec 2017, 16:51
Bunuel wrote:
Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train B leaves Boston at 7:45 am traveling to New York at 70 mph on a parallel track. If the distance between New York and Boston is 210 miles, at what time will the two trains pass each other?

A) 8:15 am
B) 8:45 am
C) 9:00 am
D) 9:30 am
E) Cannot be determined from the information given


We are given that train A is traveling at 80 mph and train B is traveling at 70 mph. Since train A leaves 45 minutes (¾ hour) before train B, we can let the time of train A = t + 3/4 and the time of train B = t.

Thus, the distance of train A is 80(t + 3/4) = 80t + 60 and the distance of train B is 70t.

Since we have a converging problem, we can use the following equation:

80t + 60 + 70t = 210

150t = 150

t = 1 hour

The trains passed each other at 7:45 + 1 hour = 8:45 a.m.

Answer: B
_________________

Jeffery Miller
Head of GMAT Instruction

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

EMPOWERgmat Instructor
User avatar
V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 12857
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train  [#permalink]

Show Tags

New post 12 Jan 2018, 11:56
Hi All,

This is an example of a Combined Rate question. These questions are typically solved with the Rate Formula and some arithmetic. For this prompt, we can also TEST THE ANSWERS.

We're given the 'start times' and rates for two trains. We're asked at what time they will pass one another.

Train A: Starts at 7am; travels 80 mph
Train B: Starts at 7:45am; travels 70 mph
Total distance between them = 210 miles

Based on these numbers, if we did some basic math, then we can figure out that at 9am Train A would have traveled 160 miles and Train B would have traveled OVER 70 miles - for a total of over 230 miles. This is clearly too much distance traveled, so the trains would have met a little before 9am. Looking at the answer choices, let's TEST Answer B...

Answer B: 8:45am

At 8:45am, Train A had traveled 1 3/4 hours at 80 mph = 140 miles
At 8:45am, Train B had traveled 1 hour at 70 mph = 70 miles
Total = 140 + 70 = 210 miles

This is an exact match for what we were told, so this must be the answer.

Final Answer:

GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free
  Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****

GMAT Club Bot
Re: Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train &nbs [#permalink] 12 Jan 2018, 11:56
Display posts from previous: Sort by

Train A leaves New York at 7:00 am traveling to Boston at 80mph. Train

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

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

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.