Marge has 3 pumps for filling her swimming pool. When all 3 : GMAT Problem Solving (PS)
Check GMAT Club App Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

It is currently 07 Dec 2016, 07:35
GMAT Club Tests

Chicago-Booth

is Releasing R1 Admission Decisions | Keep Watch on App Tracker | Join Chat Room2 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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Marge has 3 pumps for filling her swimming pool. When all 3

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

Hide Tags

2 KUDOS received
Senior Manager
Senior Manager
User avatar
Status: Final Lap
Joined: 25 Oct 2012
Posts: 287
Concentration: General Management, Entrepreneurship
GPA: 3.54
WE: Project Management (Retail Banking)
Followers: 3

Kudos [?]: 285 [2] , given: 85

Marge has 3 pumps for filling her swimming pool. When all 3 [#permalink]

Show Tags

New post 10 Feb 2013, 06:11
2
This post received
KUDOS
9
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

72% (03:38) correct 28% (02:10) wrong based on 250 sessions

HideShow timer Statistics

Marge has 3 pumps for filling her swimming pool. When all 3 pumps work at their maximum rates, the swimming pool is filled in 56 minutes. Pump 1's maximum rate is twice the maximum rate of pump 2 and four times the maximum rate of pump 3. How long would it take Marge to fill the pool if she used only pump 3 at its maximum rate ?

A) 2hrs, 48mins
B) 6hrs, 32mins
C) 7hrs, 12mins
D) 13hrs, 4mins
E) 14hrs, 24mins
[Reveal] Spoiler: OA

_________________

KUDOS is the good manner to help the entire community.

"If you don't change your life, your life will change you"

Expert Post
4 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 35911
Followers: 6851

Kudos [?]: 90015 [4] , given: 10402

Re: Marge has 3 pumps for filling her swimming pool. When all 3 [#permalink]

Show Tags

New post 10 Feb 2013, 06:32
4
This post received
KUDOS
Expert's post
4
This post was
BOOKMARKED
Rock750 wrote:
Marge has 3 pumps for filling her swimming pool. When all 3 pumps work at their maximum rates, the swimming pool is filled in 56 minutes. Pump 1's maximum rate is twice the maximum rate of pump 2 and four times the maximum rate of pump 3. How long would it take Marge to fill the pool if she used only pump 3 at its maximum rate ?

A) 2hrs, 48mins
B) 6hrs, 32mins
C) 7hrs, 12mins
D) 13hrs, 4mins
E) 14hrs, 24mins


The rate of pump 1 = 4x job/minute.
The rate of pump 2 = 2x job/minute.
The rate of pump 3 = x job/minute.

Given that x+2x+4x=1/56 --> x=1/392 --> (time) = (reciprocal of rate) = 392 minutes = 6 hours and 32 minutes.

Answer: B.
_________________

New to the Math Forum?
Please read this: 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

Expert Post
GMAT Tutor
avatar
Joined: 24 Jun 2008
Posts: 1183
Followers: 409

Kudos [?]: 1477 [0], given: 4

Re: Marge has 3 pumps for filling her swimming pool. When all 3 [#permalink]

Show Tags

New post 10 Feb 2013, 06:35
Rock750 wrote:
Marge has 3 pumps for filling her swimming pool. When all 3 pumps work at their maximum rates, the swimming pool is filled in 56 minutes. Pump 1's maximum rate is twice the maximum rate of pump 2 and four times the maximum rate of pump 3. How long would it take Marge to fill the pool if she used only pump 3 at its maximum rate ?

A) 2hrs, 48mins
B) 6hrs, 32mins
C) 7hrs, 12mins
D) 13hrs, 4mins
E) 14hrs, 24mins


I'll use letters to label the pumps rather than numbers, because there will be so many numbers elsewhere in the solution. Real GMAT questions would normally compare how long it takes each pump to fill the pool, rather than compare the rates at which each pump fills the pool. That is, a real GMAT question would say that Pump C takes four times as long as Pump A (if A's rate is four times that of C, then C takes four times as long), and that Pump B takes twice as long as Pump A.

So, say Pump A fills the pool in t minutes. Then we know:

A fills 1 pool in t minutes
B fills 1 pool in 2t minutes
C fills 1 pool in 4t minutes

You could use the rates formula now, or you can just get the same amount of time for each pump - we can use 4t minutes:

A fills 4 pools in 4t minutes
B fills 2 pools in 4t minutes
C fills 1 pool in 4t minutes

So if they all work together for 4t minutes, they fill 4+2+1 = 7 pools. If they fill 7 pools in 4t minutes, they fill 1 pool in 4t/7 minutes. This is equal to 56 minutes, from the question, so

4t/7 = 56
4t = 56*7
4t = 392

Notice that 4t is what we wanted to find - that's the time it takes pump C. So the answer is 392 minutes, or 6 hours and 32 minutes.
_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

3 KUDOS received
Intern
Intern
avatar
Joined: 06 Aug 2012
Posts: 12
Location: Russian Federation
Concentration: International Business, General Management
GMAT Date: 06-28-2013
WE: Sales (Manufacturing)
Followers: 0

Kudos [?]: 9 [3] , given: 0

GMAT ToolKit User Reviews Badge
Re: Marge has 3 pumps for filling her swimming pool. When all 3 [#permalink]

Show Tags

New post 03 Jun 2013, 23:06
3
This post received
KUDOS
My approach is quite similar to Bunuel's.
A,B,C - each pump's rate respectively. We know that all 3 pumps fill the pool for 56 min:
1/(A+B+C)=56
We also know that:
A=2B=4C; or A= 4C and B=2C

substitute these equalities in first equation:
1/(4C+2C+C)=56 ====> 1/7C=56 ===> C=1/392 meaning that pump C needs 392 minutes or 6 h 32 min to fill the pool alone.
Intern
Intern
avatar
Joined: 09 Apr 2013
Posts: 32
Location: United States
Concentration: Social Entrepreneurship, Strategy
GMAT 1: 750 Q50 V41
GPA: 3.55
Followers: 1

Kudos [?]: 38 [0], given: 0

Re: Marge has 3 pumps for filling her swimming pool. When all 3 [#permalink]

Show Tags

New post 05 Jun 2013, 09:01
I think of the fraction of the pool that each pump fills.
If the third pump fills up x, the second pump fills up 2x, and the first pump fills up 4x, so there are seven "parts" (4+2+1)
which means
First pump fills 4/7 of the pool in 56 mins
2nd pump fills 2/7 of the pool in 56 mins
3rd pump fills 1/7 of the pool in 56 mins

for the 3rd pump to fill the whole pool by itself, it would take 7 times the time. So...
56 x 7 = 392 mins = 6 hours and 32 minutes

Answer is B
1 KUDOS received
Intern
Intern
avatar
Joined: 17 Jun 2013
Posts: 3
Followers: 0

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

Re: Marge has 3 pumps for filling her swimming pool. When all 3 [#permalink]

Show Tags

New post 19 Jun 2013, 04:36
1
This post received
KUDOS
I am getting the same solution like Bunuel
Using the method of The Highest Common Factor
Given that x+2x+4x=1/56
x=1/392
= 392 minutes
= 6 hours and 32 minutes.
Director
Director
User avatar
Joined: 23 Jan 2013
Posts: 568
Schools: Cambridge'16
Followers: 1

Kudos [?]: 41 [0], given: 40

CAT Tests
Re: Marge has 3 pumps for filling her swimming pool. When all 3 [#permalink]

Show Tags

New post 26 Oct 2014, 04:28
1/x+1/2x+1/4x=1/56
7/4x=1/56
x=1/98 portion of work per minute does fastest pump.
So, slowest does 1/98*4=1/392 portion, i.e in 392 min.
392/60=6.5... or 6h.32 min

B
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 12885
Followers: 561

Kudos [?]: 158 [0], given: 0

Premium Member
Re: Marge has 3 pumps for filling her swimming pool. When all 3 [#permalink]

Show Tags

New post 31 Jan 2016, 09:44
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Intern
Intern
avatar
Joined: 26 May 2016
Posts: 12
Followers: 0

Kudos [?]: 1 [0], given: 2

CAT Tests
Re: Marge has 3 pumps for filling her swimming pool. When all 3 [#permalink]

Show Tags

New post 01 Oct 2016, 17:40
Bunuel wrote:
Rock750 wrote:
Marge has 3 pumps for filling her swimming pool. When all 3 pumps work at their maximum rates, the swimming pool is filled in 56 minutes. Pump 1's maximum rate is twice the maximum rate of pump 2 and four times the maximum rate of pump 3. How long would it take Marge to fill the pool if she used only pump 3 at its maximum rate ?

A) 2hrs, 48mins
B) 6hrs, 32mins
C) 7hrs, 12mins
D) 13hrs, 4mins
E) 14hrs, 24mins


The rate of pump 1 = 4x job/minute.
The rate of pump 2 = 2x job/minute.
The rate of pump 3 = x job/minute.

Given that x+2x+4x=1/56 --> x=1/392 --> (time) = (reciprocal of rate) = 392 minutes = 6 hours and 32 minutes.

Answer: B.


How about this approach:

Water pumped by pump 1 in 56 mins : 400 lts
Water pumped by pump 2 in 56 mins : 200 lts
Water pumped by pump 3 in 56 mins : 100 lts

total water pumped in 56 mins by all: 700 lts

Hence, pump 3 needs to pump 700 lts

for pump 3,

100 lts take 56 mins
so 700 lts will take 56 * 7 = 350 + 42 = 392mins = 392/60 hours = 6 hours and 32 mins.
Expert Post
VP
VP
User avatar
Joined: 08 Jul 2010
Posts: 1432
Location: India
GMAT: INSIGHT
WE: Education (Education)
Followers: 65

Kudos [?]: 1340 [0], given: 42

Re: Marge has 3 pumps for filling her swimming pool. When all 3 [#permalink]

Show Tags

New post 09 Nov 2016, 23:41
Rock750 wrote:
Marge has 3 pumps for filling her swimming pool. When all 3 pumps work at their maximum rates, the swimming pool is filled in 56 minutes. Pump 1's maximum rate is twice the maximum rate of pump 2 and four times the maximum rate of pump 3. How long would it take Marge to fill the pool if she used only pump 3 at its maximum rate ?

A) 2hrs, 48mins
B) 6hrs, 32mins
C) 7hrs, 12mins
D) 13hrs, 4mins
E) 14hrs, 24mins


Answer: Option B

Please check attachment
Attachments

File comment: www.GMATinsight.com
3.jpg
3.jpg [ 59.66 KiB | Viewed 371 times ]


_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com
Call us : +91-9999687183 / 9891333772
http://www.GMATinsight.com/testimonials.html



Feel free to give a Kudos if it is a useful post .

Math Forum Moderator
User avatar
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 2103
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
Followers: 82

Kudos [?]: 556 [0], given: 310

GMAT ToolKit User Premium Member CAT Tests
Re: Marge has 3 pumps for filling her swimming pool. When all 3 [#permalink]

Show Tags

New post 10 Nov 2016, 09:31
Rock750 wrote:
Marge has 3 pumps for filling her swimming pool. When all 3 pumps work at their maximum rates, the swimming pool is filled in 56 minutes. Pump 1's maximum rate is twice the maximum rate of pump 2 and four times the maximum rate of pump 3. How long would it take Marge to fill the pool if she used only pump 3 at its maximum rate ?

A) 2hrs, 48mins
B) 6hrs, 32mins
C) 7hrs, 12mins
D) 13hrs, 4mins
E) 14hrs, 24mins


Ratio of efficiency of the 3 pumps is -

Pump - I : Pump - II : Pump - III = 4 : 2 : 1

Total capacity is 56*7

Time taken to fill the tank using only Pump - III = \(\frac{56*7}{60}\) = 6 Hrs 32 minutes...

Hence, Answer will be (B) 6hrs, 32mins
_________________

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 )

Re: Marge has 3 pumps for filling her swimming pool. When all 3   [#permalink] 10 Nov 2016, 09:31
    Similar topics Author Replies Last post
Similar
Topics:
1 Experts publish their posts in the topic A pipe fills a pool in 3.5 hours. If the flow of water is changed so Bunuel 3 03 Oct 2016, 22:33
9 Experts publish their posts in the topic Working alone, pump A can empty a pool in 3 hours. Working alone, pump Bunuel 10 23 Mar 2015, 05:34
8 Experts publish their posts in the topic A group of 3 small pumps and 1 large pump is filling a tank. Each of t jgk 3 01 Nov 2014, 09:39
17 Experts publish their posts in the topic A pool which was 2/3 full to begin with, was filled at a macjas 11 02 Jun 2012, 22:51
10 Experts publish their posts in the topic A pump started filling an empty pool with water and continue Jcpenny 8 20 Nov 2008, 10:30
Display posts from previous: Sort by

Marge has 3 pumps for filling her swimming pool. When all 3

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


GMAT Club MBA Forum Home| About| 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®.