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

It is currently 24 Apr 2014, 03:19

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

Marla starts running around a circular track at the same

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Director
Director
Status: Preparing for the 4th time -:(
Joined: 25 Jun 2011
Posts: 562
Location: United Kingdom
Concentration: International Business, Strategy
GMAT Date: 06-22-2012
GPA: 2.9
WE: Information Technology (Consulting)
Followers: 11

Kudos [?]: 129 [0], given: 217

GMAT Tests User CAT Tests
Marla starts running around a circular track at the same [#permalink] New post 16 Mar 2012, 06:55
00:00
A
B
C
D
E

Difficulty:

  25% (low)

Question Stats:

77% (02:30) correct 22% (01:28) wrong based on 98 sessions
Marla starts running around a circular track at the same time Nick starts walking around the same circular track. Marla completes 32 laps around the track per hour and Nick completes 12 laps around the track per hour. How many minutes after Marla and Nick begin moving will Marla have completed 4 more laps around the track than Nick?

(A) 5
(B) 8
(C) 12
(D) 15
(E) 20

How to do this guys?
[Reveal] Spoiler: OA

_________________

Best Regards,
E.

MGMAT 1 --> 530
MGMAT 2--> 640
MGMAT 3 ---> 610 :-(

1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 17394
Followers: 2889

Kudos [?]: 18492 [1] , given: 2361

GMAT Tests User CAT Tests
Re: Marla starts running around a circular track at the same [#permalink] New post 16 Mar 2012, 08:26
1
This post received
KUDOS
Expert's post
enigma123 wrote:
Marla starts running around a circular track at the same time Nick starts walking around the same circular track. Marla completes 32 laps around the track per hour and Nick completes 12 laps around the track per hour. How many minutes after Marla and Nick begin moving will Marla have completed 4 more laps around the track than Nick?

(A) 5
(B) 8
(C) 12
(D) 15
(E) 20

How to do this guys?


Marla completes 32-20=20 more laps in 1 hour. Marla to complete 4 (20/5=4) more laps will need 1/5 hours, which is 12 minutes.

Answer: C.
_________________

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

Manager
Manager
Joined: 12 Mar 2012
Posts: 95
Location: India
Concentration: Technology, Strategy
GMAT 1: 710 Q49 V36
GPA: 3.2
WE: Information Technology (Computer Software)
Followers: 9

Kudos [?]: 260 [0], given: 22

Re: Marla starts running around a circular track at the same [#permalink] New post 16 Mar 2012, 10:00
Marla completes 32laps/60min, Nick completes 12laps/60mins.
After x mins Marla would have completed 4 laps more than Nick had completed.
x((32-12)/60) = 4,
x*20/60 = 4,
x = 12 mins.
Director
Director
Status: Preparing for the 4th time -:(
Joined: 25 Jun 2011
Posts: 562
Location: United Kingdom
Concentration: International Business, Strategy
GMAT Date: 06-22-2012
GPA: 2.9
WE: Information Technology (Consulting)
Followers: 11

Kudos [?]: 129 [0], given: 217

GMAT Tests User CAT Tests
Re: Marla starts running around a circular track at the same [#permalink] New post 16 Mar 2012, 15:46
Bunuel - how did you get this?

Marla to complete 4 (20/5=4) more laps will need 1/5 hours, which is 12 minutes.
_________________

Best Regards,
E.

MGMAT 1 --> 530
MGMAT 2--> 640
MGMAT 3 ---> 610 :-(

Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 17394
Followers: 2889

Kudos [?]: 18492 [0], given: 2361

GMAT Tests User CAT Tests
Re: Marla starts running around a circular track at the same [#permalink] New post 16 Mar 2012, 15:53
Expert's post
enigma123 wrote:
Bunuel - how did you get this?

Marla to complete 4 (20/5=4) more laps will need 1/5 hours, which is 12 minutes.


Since Marla completes 20 more laps in 1 hour, then to complete 1/5 th of 20 laps (4 laps) she will need 1/5 th of an hour, which is 12 minutes.
_________________

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

Manager
Manager
Joined: 14 Dec 2011
Posts: 65
GMAT 1: 630 Q48 V29
GMAT 2: 690 Q48 V37
Followers: 1

Kudos [?]: 4 [0], given: 24

GMAT Tests User
Re: Marla starts running around a circular track at the same [#permalink] New post 17 Mar 2012, 06:06
Best way is to use plug in!

Always plug in C first, since this is the median value!

In 12 minutes she will have completed 32/5 rounds ( /5 because 12min is 1/5 hours) and he will have completed 12/5 rounds.

32/5 = 6 2/5
12/5 = 2 2/5

4 is the difference and hence C is th answer.



Sometimes you get lucky and plug in the right answer first! Will help you save heaps of time!
Manager
Manager
User avatar
Joined: 15 Jan 2011
Posts: 107
Followers: 7

Kudos [?]: 18 [0], given: 13

Re: Marla starts running around a circular track at the same [#permalink] New post 12 Apr 2012, 03:35
Maria's rate - 32 laps per hour --> 32/60 laps/min
Nick's rate - 12 laps per hour --> 12/60 laps/min

lets set equations:

32/60*t=4 (since Maria had to run 4 laps before Nick would start)
12/60*t=0 (Hick has just started and hasn't run any lap yet)
-----------------------------------
(32/60-12/60)*t=4-0 (since Nick was chasing Maria)
t=12 min needed Maria to run 4 laps
Senior Manager
Senior Manager
User avatar
Joined: 28 Jun 2009
Posts: 455
Location: United States (MA)
Followers: 14

Kudos [?]: 95 [0], given: 46

GMAT Tests User
Re: Marla starts running around a circular track at the same [#permalink] New post 23 Apr 2012, 14:27
I say C. 12 mins.

Marla's speed : 32/60 laps per min
Nick's speed : 12/60 laps per min

So by plugging in ans choices,

at 12 mins, Marla : 6.4 laps, Nick 2.4 laps.
Intern
Intern
Joined: 06 Mar 2012
Posts: 21
Concentration: International Business, Finance
GMAT Date: 08-04-2012
WE: Consulting (Accounting)
Followers: 0

Kudos [?]: 17 [0], given: 2

GMAT Tests User
Re: Marla starts running around a circular track at the same [#permalink] New post 23 Apr 2012, 20:50
I also got C (12).

t= time
32 laps per hour * t = 12 laps per hour * t + 4 laps

32t = 12t + 4
20t = 4
t= 1/5 hr

1/5(60min)= 12 mins

I believe the recommended strategy is to change to minutes right away but in this situation I found it easier to do it at the end because of how the rates simplified per minute.
_________________

make each day your masterpiece

Intern
Intern
Joined: 28 Feb 2012
Posts: 22
GMAT 1: 700 Q48 V39
WE: Information Technology (Computer Software)
Followers: 0

Kudos [?]: 8 [0], given: 3

Re: Marla starts running around a circular track at the same [#permalink] New post 23 Apr 2012, 21:28
In 15 min - Marla has completed 32/4 = 8 laps and Nick -> 12/4 = 3
the difference at 15 mins is 5 laps. So plugging in C.

In 12 mins - Marla has completed 32/5 = 6.4laps while Nick has completed 12/5 = 2.4 laps , a difference of 4 laps.

So ans - C
Intern
Intern
Joined: 19 Aug 2011
Posts: 30
Concentration: Finance, Entrepreneurship
Followers: 0

Kudos [?]: 6 [0], given: 2

Re: Marla starts running around a circular track at the same [#permalink] New post 23 Apr 2012, 22:32
In 1 min:
Marla runs: 32/60 = 8/15 laps
Nick walks: 12/60 = 1/5 laps

Let x be the number of minutes required for Marla to be 4 laps ahead of Nick.
x * 1/5 + 4 = x * 8/15
x =12 mins
Intern
Intern
Joined: 29 Feb 2012
Posts: 12
Followers: 0

Kudos [?]: 0 [0], given: 1

Re: Marla starts running around a circular track at the same [#permalink] New post 25 Apr 2012, 01:21
The answer is C
use relative velocity to solve it

the relative velocity would be (32-12) in 1 hour.
hence, 20 laps in 1 hour
therefore time to complete four laps is 1/5hr
12 mins
Intern
Intern
Joined: 11 Sep 2013
Posts: 25
Followers: 0

Kudos [?]: 0 [0], given: 55

CAT Tests
Re: Marla starts running around a circular track at the same [#permalink] New post 21 Apr 2014, 01:10
Let time be t
32/60t-12/60t=4 so t=12
Senior Manager
Senior Manager
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 418
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Followers: 1

Kudos [?]: 73 [0], given: 153

Re: Marla starts running around a circular track at the same [#permalink] New post 21 Apr 2014, 22:01
Let the one lap distance = d
Speed of Marla = \frac{32}{60}
Speed of Nick = \frac{12}{60}
Time t would be same in both the cases

Setting up the equation

d = \frac{32}{60}* t ............ (1)

d-4 = \frac{12}{60} * t........(2)

Equating (1) & (2)

\frac{12}{60} * t + 4 = \frac{32}{60} * t

\frac{1}{3} * t = 4

t = 12

Answer = C
_________________

Kindly press "Kudos" to appreciate

Re: Marla starts running around a circular track at the same   [#permalink] 21 Apr 2014, 22:01
    Similar topics Author Replies Last post
Similar
Topics:
New posts A, B and C run around a circular track starting from the shahnandan 4 02 Mar 2006, 03:14
New posts A, B and C run around a circular track starting from the kyatin 3 23 Mar 2007, 15:00
New posts A, B, C run a circular track starting from the same point mbunny 7 12 May 2007, 12:44
New posts A, B and C run around a circular track starting from the FN 5 28 Aug 2007, 18:29
This topic is locked, you cannot edit posts or make further replies. New 12 Marla starts running around a circular track at the same gmatcracker24 17 07 Oct 2011, 08:09
Display posts from previous: Sort by

Marla starts running around a circular track at the same

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

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®.