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

It is currently 17 Oct 2018, 20:37

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

A woman is planning a trip that involves 3 connecting trains

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

Hide Tags

Senior Manager
Senior Manager
User avatar
Joined: 21 Oct 2013
Posts: 420
A woman is planning a trip that involves 3 connecting trains  [#permalink]

Show Tags

New post 13 Jan 2014, 13:07
4
4
00:00
A
B
C
D
E

Difficulty:

  85% (hard)

Question Stats:

63% (03:31) correct 37% (03:09) wrong based on 221 sessions

HideShow timer Statistics

A woman is planning a trip that involves 3 connecting trains that depart from Stations X, Y, and Z, respectively. The first train leaves Station X every hour, beginning at 6 a.m., and arrives at Station Y 1(3/4) hours later. The second train leaves Station Y every half hour, beginning at 9 a.m., and arrives at Station Z 2(1/3) hours later. The third train leaves Station Z every 45 minutes, beginning at 8 a.m. What is the least total amount of time the woman must spend waiting between trains if all trains depart and arrive on schedule, and if she arrives at Station Z no later than 3:30 p.m.?
15 minutes
25 minutes
1 hour 15 minutes
1 hour 40 minutes
4 hours 30 minutes

OE
Trains coming from X arrive at Y at 45 minutes past the hour.
Trains leave Y on the hour and the half-hour. So minimum wait at Y will be 0:15.
This could be 8:45 − 9:00 am, 9:45 − 10:00 am, 10:45 − 11:00 am, etc.

Trains from Y will reach Z at 20 and 50 minutes past the hour, with the first arriving at 11:20.

Trains leave Z at various times, creating waits as short as 10 minutes (12:20-12:30) and as long as 40 minutes (11:50-12:30).

For shortest total waiting time possible, need to combine a 15-minute wait for the second train with a 10-minute wait for third train.

This will happen if the woman takes the 8:00 train from X, the 10:00 train from Y, and the 12:30 train from Z.


Hi, I found the situation of this question is not very clear.. I want to know how we can approach this, please.
Most Helpful Expert Reply
Veritas Prep GMAT Instructor
User avatar
P
Joined: 16 Oct 2010
Posts: 8386
Location: Pune, India
Re: A woman is planning a trip that involves 3 connecting trains  [#permalink]

Show Tags

New post 02 Mar 2015, 02:28
7
1
goodyear2013 wrote:
A woman is planning a trip that involves 3 connecting trains that depart from Stations X, Y, and Z, respectively. The first train leaves Station X every hour, beginning at 6 a.m., and arrives at Station Y 1(3/4) hours later. The second train leaves Station Y every half hour, beginning at 9 a.m., and arrives at Station Z 2(1/3) hours later. The third train leaves Station Z every 45 minutes, beginning at 8 a.m. What is the least total amount of time the woman must spend waiting between trains if all trains depart and arrive on schedule, and if she arrives at Station Z no later than 3:30 p.m.?
15 minutes
25 minutes
1 hour 15 minutes
1 hour 40 minutes
4 hours 30 minutes

OE
Trains coming from X arrive at Y at 45 minutes past the hour.
Trains leave Y on the hour and the half-hour. So minimum wait at Y will be 0:15.
This could be 8:45 − 9:00 am, 9:45 − 10:00 am, 10:45 − 11:00 am, etc.

Trains from Y will reach Z at 20 and 50 minutes past the hour, with the first arriving at 11:20.

Trains leave Z at various times, creating waits as short as 10 minutes (12:20-12:30) and as long as 40 minutes (11:50-12:30).

For shortest total waiting time possible, need to combine a 15-minute wait for the second train with a 10-minute wait for third train.

This will happen if the woman takes the 8:00 train from X, the 10:00 train from Y, and the 12:30 train from Z.


Hi, I found the situation of this question is not very clear.. I want to know how we can approach this, please.


Make a departure arrival diagram to minimize the waiting time.
Attachment:
FullSizeRender.jpg
FullSizeRender.jpg [ 1.49 MiB | Viewed 3187 times ]

Trains depart from X at 6/7/8/9 and reach Y at 7:45/8:45/9:45 etc
Trains depart from Y at 9/9:30/10/10:30 etc. This means a minimum wait of 15 mins is required at Y.
They arrive at Z at 11:20/11:50/12:20/12:50. They depart from Z at 8/8:45/9:30/10:15/11/11:45/12:30 and so on. Note that if she arrives at Z at 20 mins past the hour, she will need to wait for at least 10 mins for 12:30/3:30 etc train. If she arrives at 50 mins past the hour, again she needs to wait for at least 10 mins to take the 2 o clock train. So anyway 10 mins at Z is a given.

So minimum she will need to wait for 15+10 = 25 mins.
This works out if she takes 8 o clock train from X, reaches Y at 9:45, takes 10 o clock train from Y and reaches Z at 12:20 and takes 12:30 train from Z.

Answer (B)
_________________

Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >

GMAT self-study has never been more personalized or more fun. Try ORION Free!

General Discussion
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 49968
Re: A woman is planning a trip that involves 3 connecting trains  [#permalink]

Show Tags

New post 13 Jan 2014, 13:15
goodyear2013 wrote:
A woman is planning a trip that involves 3 connecting trains that depart from Stations X, Y, and Z, respectively. The first train leaves Station X every hour, beginning at 6 a.m., and arrives at Station Y 1(3/4) hours later. The second train leaves Station Y every half hour, beginning at 9 a.m., and arrives at Station Z 2(1/3) hours later. The third train leaves Station Z every 45 minutes, beginning at 8 a.m. What is the least total amount of time the woman must spend waiting between trains if all trains depart and arrive on schedule, and if she arrives at Station Z no later than 3:30 p.m.?
15 minutes
25 minutes
1 hour 15 minutes
1 hour 40 minutes
4 hours 30 minutes

OE
Trains coming from X arrive at Y at 45 minutes past the hour.
Trains leave Y on the hour and the half-hour. So minimum wait at Y will be 0:15.
This could be 8:45 − 9:00 am, 9:45 − 10:00 am, 10:45 − 11:00 am, etc.

Trains from Y will reach Z at 20 and 50 minutes past the hour, with the first arriving at 11:20.

Trains leave Z at various times, creating waits as short as 10 minutes (12:20-12:30) and as long as 40 minutes (11:50-12:30).

For shortest total waiting time possible, need to combine a 15-minute wait for the second train with a 10-minute wait for third train.

This will happen if the woman takes the 8:00 train from X, the 10:00 train from Y, and the 12:30 train from Z.


Hi, I found the situation of this question is not very clear.. I want to know how we can approach this, please.


This is a reworded OG question: an-airline-passenger-is-planning-a-trip-that-involves-three-108830.html
_________________

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

Manager
Manager
avatar
Joined: 12 Oct 2014
Posts: 50
Location: India
Concentration: Finance, General Management
GMAT 1: 550 Q44 V21
WE: Analyst (Investment Banking)
A woman is planning a trip that involves 3 connecting trains  [#permalink]

Show Tags

New post 19 Jun 2015, 07:16
1
I would prefer back solving for this question.

Reached Z @ 3:30 PM, from Y-->Z it will take 140 minutes, so she should have started from Y @ 1:10 PM but trains from Y to Z leaves at every 30mins starting at 9am,therefore she should board into the train @1PM and wait at station Z for 10minutes for her next train from station Z.

Now, X --> Y journey:


To reach Y at 1PM she should start from X by 11AM atleast as, journey time is 105minutes .If she will start from station X by 11AM then she will reach Y by 12:45 PM, hence will wait for 15minutes before she board into 1PM train from station Y.

Total waiting time= 15+10=25 minutes.

Hope that was helpful.

Cheers,
Gaurav :)
Board of Directors
User avatar
P
Joined: 17 Jul 2014
Posts: 2655
Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30
GPA: 3.92
WE: General Management (Transportation)
GMAT ToolKit User Premium Member Reviews Badge
Re: A woman is planning a trip that involves 3 connecting trains  [#permalink]

Show Tags

New post 13 Jan 2016, 19:36
kind of tricky one...but as bunuel said..looks like an og question...
if passenger leaves at 8AM, then arrives at Y at 9:45AM, departs at 10AM, or waits 15 minutes (always 15 mins, since the timing is always 15 mins either behind or late)

trains at Z depart at 8:45, 9:30, 10:15, 11:00, 11:45, 12:30, 1:15PM, 2PM, 2:45PM
8:45, 9:30, 10:15, and 11:00 can't be, so right away out. note that the train from Y to Z alone takes 2h20min, and train Y starts at 9AM.
if starts at 9AM, then it will arrive at Z at 11:20, which makes 25 mins wait time at Z.
if starts at 9:30 -> arrives at 11:50 - wait time - 40 minutes. nope
if starts at 10 -> arrives at 12:20 - wait time 10 minutes.
if starts at 10:30 -> arrives at 12:50 -> wait time 25 minutes
if starts at 11 -> arrives at 1:20PM, wait time 40 minutes.
if starts at 11:30 -> arrives at 1:50 -> wait time 10 minutes.
if starts at 12 -> arrives at 12:20 -> wait time 25 mins.
thus, the min time to wait would be 10 mins at Z.
15+10 = 25
can't be 15, since the time to wait at Y only is 15, and there is no such way that there is no wait time at Z.
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2830
Re: A woman is planning a trip that involves 3 connecting trains  [#permalink]

Show Tags

New post 19 Apr 2018, 16:58
goodyear2013 wrote:
A woman is planning a trip that involves 3 connecting trains that depart from Stations X, Y, and Z, respectively. The first train leaves Station X every hour, beginning at 6 a.m., and arrives at Station Y 1(3/4) hours later. The second train leaves Station Y every half hour, beginning at 9 a.m., and arrives at Station Z 2(1/3) hours later. The third train leaves Station Z every 45 minutes, beginning at 8 a.m. What is the least total amount of time the woman must spend waiting between trains if all trains depart and arrive on schedule, and if she arrives at Station Z no later than 3:30 p.m.?
15 minutes
25 minutes
1 hour 15 minutes
1 hour 40 minutes
4 hours 30 minutes


We see that the total wait time is the total time waiting at stations Y and Z assuming that she doesn’t have to wait at station X. Let’s also let the trains leaving at stations X, Y and Z be trains X, Y and Z, respectively.

Assuming she arrives at station X exactly on the hour, except for arriving at 6 am at station X, she must wait 15 minutes at station Y for train Y. For example, if she catches train X at station X at 7 am, she will arrive at station Y at 8:45 am and catch train Y at 9 am. If she catches train X at station X at 8 am, she will arrive at station Y at 9:45 am and catch train Y at 10 am.

We see that the minimum wait time at station Y is 15 minutes. Now let’s see how we can minimize the wait time at station Z. Since train Z leaves station Z every 45 minutes beginning at 8 am, train Z leaves station Z at 8 am, 8:45 am, 9:30 am, 10:15 am, 11 am, 11:45 am, 12:30 pm, etc. Also, since train Y takes 2 hours and 20 minutes to arrive at station Z and it leaves station Y every 30 minutes beginning at 9 am, train Y will arrive at station Z at 11:20 am, 11:50 am, 12:20 pm, etc. We see that the minimum wait time is 10 minutes if she can arrive at station Z at 12:20 pm and take train Z at 12:30 pm.

Thus the minimum total wait time is 15 + 10 = 25 minutes.

Answer: B
_________________

Jeffery Miller
Head of GMAT Instruction

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

GMAT Club Bot
Re: A woman is planning a trip that involves 3 connecting trains &nbs [#permalink] 19 Apr 2018, 16:58
Display posts from previous: Sort by

A woman is planning a trip that involves 3 connecting trains

  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®.