It is currently 24 Nov 2017, 06:30

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Marla starts running around a circular track at the same

Author Message
TAGS:

### Hide Tags

Director
Status: Finally Done. Admitted in Kellogg for 2015 intake
Joined: 25 Jun 2011
Posts: 532

Kudos [?]: 4237 [1], given: 217

Location: United Kingdom
GMAT 1: 730 Q49 V45
GPA: 2.9
WE: Information Technology (Consulting)
Marla starts running around a circular track at the same [#permalink]

### Show Tags

16 Mar 2012, 07:55
1
KUDOS
21
This post was
BOOKMARKED
00:00

Difficulty:

35% (medium)

Question Stats:

74% (01:54) correct 26% (02:06) wrong based on 522 sessions

### HideShow timer Statistics

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
GMAT ==> 730

Kudos [?]: 4237 [1], given: 217

Math Expert
Joined: 02 Sep 2009
Posts: 42356

Kudos [?]: 133204 [7], given: 12439

Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

16 Mar 2012, 09:26
7
KUDOS
Expert's post
3
This post was
BOOKMARKED
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.

_________________

Kudos [?]: 133204 [7], given: 12439

Manager
Joined: 12 Mar 2012
Posts: 93

Kudos [?]: 351 [0], given: 22

Location: India
Concentration: Technology, Strategy
GMAT 1: 710 Q49 V36
GPA: 3.2
WE: Information Technology (Computer Software)
Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

16 Mar 2012, 11:00
1
This post was
BOOKMARKED
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.

Kudos [?]: 351 [0], given: 22

Director
Status: Finally Done. Admitted in Kellogg for 2015 intake
Joined: 25 Jun 2011
Posts: 532

Kudos [?]: 4237 [0], given: 217

Location: United Kingdom
GMAT 1: 730 Q49 V45
GPA: 2.9
WE: Information Technology (Consulting)
Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

16 Mar 2012, 16:46
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
GMAT ==> 730

Kudos [?]: 4237 [0], given: 217

Math Expert
Joined: 02 Sep 2009
Posts: 42356

Kudos [?]: 133204 [3], given: 12439

Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

16 Mar 2012, 16:53
3
KUDOS
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.
_________________

Kudos [?]: 133204 [3], given: 12439

Manager
Joined: 14 Dec 2011
Posts: 61

Kudos [?]: 50 [0], given: 24

GMAT 1: 630 Q48 V29
GMAT 2: 690 Q48 V37
Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

17 Mar 2012, 07:06
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!

Kudos [?]: 50 [0], given: 24

Manager
Joined: 16 Jan 2011
Posts: 111

Kudos [?]: 180 [1], given: 15

Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

12 Apr 2012, 04:35
1
KUDOS
1
This post was
BOOKMARKED
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

Kudos [?]: 180 [1], given: 15

Senior Manager
Joined: 28 Jun 2009
Posts: 440

Kudos [?]: 194 [0], given: 46

Location: United States (MA)
Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

23 Apr 2012, 15:27
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.

Kudos [?]: 194 [0], given: 46

Intern
Joined: 06 Mar 2012
Posts: 30

Kudos [?]: 31 [1], given: 32

Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

23 Apr 2012, 21:50
1
KUDOS
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.

Kudos [?]: 31 [1], given: 32

Intern
Joined: 28 Feb 2012
Posts: 22

Kudos [?]: 12 [0], given: 3

GMAT 1: 700 Q48 V39
WE: Information Technology (Computer Software)
Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

23 Apr 2012, 22:28
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

Kudos [?]: 12 [0], given: 3

Intern
Joined: 19 Aug 2011
Posts: 27

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

Concentration: Finance, Entrepreneurship
Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

23 Apr 2012, 23:32
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

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

Intern
Joined: 29 Feb 2012
Posts: 10

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

Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

25 Apr 2012, 02:21
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

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

Manager
Joined: 11 Sep 2013
Posts: 149

Kudos [?]: 150 [0], given: 161

Concentration: Finance, Finance
Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

21 Apr 2014, 02:10
Let time be t
32/60t-12/60t=4 so t=12

Kudos [?]: 150 [0], given: 161

SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1851

Kudos [?]: 2724 [2], given: 193

Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

21 Apr 2014, 23:01
2
KUDOS
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

_________________

Kindly press "+1 Kudos" to appreciate

Kudos [?]: 2724 [2], given: 193

Senior Manager
Joined: 28 Apr 2014
Posts: 272

Kudos [?]: 40 [0], given: 46

Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

02 May 2014, 03:43
Bunuel wrote:
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.

I believe you used the concept of relative speed over here as well Bunuel . Isn't it so ? Relative speed of Bunue is 20 laps/hr so 4 laps in 1/5 of an hr = 12 minutes

Kudos [?]: 40 [0], given: 46

Director
Joined: 07 Dec 2014
Posts: 839

Kudos [?]: 273 [1], given: 15

Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

27 Dec 2015, 12:57
1
KUDOS
marla runs 32/60=8/15 laps per minute
nick walks 12/60=3/15 laps per minute
marla gains 8/15-3/15=1/3 laps per minute
4 laps/1/3 lap per minute=12 minutes

Kudos [?]: 273 [1], given: 15

Intern
Joined: 19 Aug 2016
Posts: 4

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

Marla starts running around a circular track at the same [#permalink]

### Show Tags

23 Mar 2017, 14:39
Why to make it more difficult than it is?

Marla walks 32 laps in 1 hour and spends x hours on the road. Laps covered = 32x
Nick walks 12 laps in 1 hour and spends x hours on the road. Laps covered = 12x (which must be 4 laps fewer than Marla)

32x-12x=4
x=0.2h=12 min (C)

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

Manager
Joined: 30 May 2012
Posts: 220

Kudos [?]: 82 [0], given: 151

Location: United States (TX)
Concentration: Finance, Marketing
GPA: 3.3
WE: Information Technology (Consulting)
Marla starts running around a circular track at the same [#permalink]

### Show Tags

26 Sep 2017, 10:43
Given, the distance traveled by Marla in 60 minutes = 32
Distance traveled by Marla in 't' mins = $$\frac{32t}{60}$$

Also given, the distance traveled by Nick in 60 minutes = 12
Distance traveled by Nick in 't' mins = $$\frac{12t}{60}$$

Prompt says there will be a difference of 4 laps at some point in time between the above two distances.

Since Maria travels faster, the distance covered by Maria will be more than the distance covered by Nick. Therefore, subtract the distance traveled by Nick from the distance traveled by Maria in order to avoid a negative resultant.

$$\frac{32t}{60}$$ - $$\frac{12t}{60}$$ = 4

Solving,
$$\frac{20t}{60}$$ = 4
$$\frac{t}{3}$$ = 4

t= 12 mins.

Kudos [?]: 82 [0], given: 151

Target Test Prep Representative
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 1713

Kudos [?]: 922 [0], given: 5

Re: Marla starts running around a circular track at the same [#permalink]

### Show Tags

29 Sep 2017, 10:33
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

We can use the following formula:

time = change in distance/change in rate

time = 4/20 = 1/5 hour = 12 minutes

Alternate Solution:

Note that Marla’s rate is 32/60 laps per minute and Nick’s rate is 12/60 laps per minute. Let’s say after t minutes, Marla completes 4 more laps than Nick. Then, in t minutes Marla completes 32t/60 laps and Nick completes 12t/60 laps. Since the number of laps completed by Marla is 4 more than the number completed by Nick, we have:

32t/60 = 12t/60 + 4

32t/60 - 12t/60 = 4

20t/60 = 4

t/3 = 4

t = 12

_________________

Jeffery Miller

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

Kudos [?]: 922 [0], given: 5

Re: Marla starts running around a circular track at the same   [#permalink] 29 Sep 2017, 10:33
Display posts from previous: Sort by

# Marla starts running around a circular track at the same

 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®.