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

 It is currently 18 Jan 2019, 21:12

### 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 January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar
• ### Free GMAT Strategy Webinar

January 19, 2019

January 19, 2019

07:00 AM PST

09:00 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.
• ### FREE Quant Workshop by e-GMAT!

January 20, 2019

January 20, 2019

07:00 AM PST

07:00 AM PST

Get personalized insights on how to achieve your Target Quant Score.

# An empty pool being filled with water at a constant rate takes 8 hours

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 52285
An empty pool being filled with water at a constant rate takes 8 hours  [#permalink]

### Show Tags

07 Feb 2011, 00:20
1
10
00:00

Difficulty:

15% (low)

Question Stats:

78% (01:17) correct 22% (01:23) wrong based on 1172 sessions

### HideShow timer Statistics

An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?

(A) 5 hr 30 min
(B) 5 hr 20 min
(C) 4 hr 48 min
(D) 3 hr 12 min
(E) 2 hr 40 min

_________________
Math Expert
Joined: 02 Sep 2009
Posts: 52285
An empty pool being filled with water at a constant rate takes 8 hours  [#permalink]

### Show Tags

20 Dec 2012, 04:53
4
10
An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?

(A) 5 hr 30 min
(B) 5 hr 20 min
(C) 4 hr 48 min
(D) 3 hr 12 min
(E) 2 hr 40 min

As pool is filled to 3/5 of its capacity then 2/5 of its capacity is left to fill.

Since it takes 8 hours to fill 3/5 of the pool, then to fill 2/5 of the pool it will take $$\frac{8}{(\frac{3}{5})}*\frac{2}{5} = \frac{16}{3} \ hours = 5 \ hours \ 20 \ minutes$$ (because if t is the time needed to fill the pool then $$t*\frac{3}{5}=8$$ --> $$t=8*\frac{5}{3} \ hours$$ --> to fill 2/5 of the pool $$8*\frac{5}{3}*\frac{2}{5}=\frac{16}{3}$$ hours will be needed).

Or plug values: take the capacity of the pool to be 5 liters --> 3/5 of the pool or 3 liters is filled in 8 hours, which gives the rate of 3/8 liters per hour --> remaining 2 liters will require: $$time = \frac{job}{rate} = \frac{2}{(\frac{3}{8})} = \frac{16}{3} \ hours = 5 \ hours \ 20 \ minutes$$.

_________________
Current Student
Joined: 26 May 2005
Posts: 505
Re: An empty pool being filled with water at a constant rate takes 8 hours  [#permalink]

### Show Tags

Updated on: 10 Jun 2011, 23:08
6
Its B
I would use percentages to do this ... easy for me

3/5 work = 60% = is done in 8 hrs
remaining will be 40%( percentages are always 100) be done in 8*40/60 = 16/3 = 5 1/3 hrs = 5+1/3*60 = 5.20 hrs

PS:Edited for a typo

Originally posted by sudhir18n on 10 Jun 2011, 23:05.
Last edited by sudhir18n on 10 Jun 2011, 23:08, edited 2 times in total.
##### General Discussion
Manager
Joined: 08 Sep 2010
Posts: 129
Re: An empty pool being filled with water at a constant rate takes 8 hours  [#permalink]

### Show Tags

11 Jun 2011, 09:47
3
1st convert to mins to avoid the confusion

60% = 480 mins
therefore 40% (remaining) = 320 mins (using unitary method)

320 mins = 5 hrs 20 mins
_________________

My will shall shape the future. Whether I fail or succeed shall be no man's doing but my own.

If you like my explanations award kudos.

Manager
Joined: 08 Dec 2012
Posts: 61
Location: United Kingdom
WE: Engineering (Consulting)
Re: An empty pool being filled with water at a constant rate takes 8 hours  [#permalink]

### Show Tags

26 Jan 2013, 04:33
3
2
I tried using just ratios to solve this (because rate is constant):

8Hrs to fill 3/5 tank i.e 0.6 of the tank
X hrs to fill 2/5 tank i.e 0.4 of the tank

=> 8/0.6 = X/0.4
=> X=3.2/0.6 = 32/6 = 16/3 = 5.33hrs i.e 5hr20min
Manager
Joined: 30 Jul 2013
Posts: 62
Concentration: Technology, General Management
GMAT Date: 07-03-2015
GPA: 3.8
WE: Information Technology (Computer Software)
Re: An empty pool being filled with water at a constant rate takes 8 hours  [#permalink]

### Show Tags

29 May 2015, 20:03
As per what I did,

8 Hours - 3/5 of capacity
? Time - to fill remaining - 2/5 of capacity.

But the answer I am getting is incorrect. Could someone share the appropriate process to work on this?
_________________

On the Kudos Spree.

If you like my post/comment please appreciate with kudos

EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 13347
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: An empty pool being filled with water at a constant rate takes 8 hours  [#permalink]

### Show Tags

29 May 2015, 20:08
1
1
Hi Pretz,

There are a couple of different ways to approach the math in this question. It looks like you started to set up a ratio, but didn't complete the work. Here's one way to go about it:

Since it takes 8 hours to fill 3/5 of the pool and X hours to fill 2/5 of the pool.....

8/X = (3/5)/(2/5)

Since both fractions are "over 5", we can multiply those 5s out (by multiplying the numerator and denominator by 5)....

8/X = 3/2

Now we can cross-multiply and solve for X....

16 = 3X
16/3 = X
5 1/3 hours = X

5 1/3 hours = 5 hours 20 minutes

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 Tutor Joined: 24 Jun 2008 Posts: 1323 Re: An empty pool being filled with water at a constant rate takes 8 hours [#permalink] ### Show Tags 29 May 2015, 20:53 1 If it takes 8 hours to fill 3/5 of the pool, then it takes 8/3 hours to fill 1/5 of the pool, and it thus takes 16/3 hours to fill 2/5 of the pool, which is what we need to do. _________________ 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 SVP Joined: 06 Nov 2014 Posts: 1877 Re: An empty pool being filled with water at a constant rate takes 8 hours [#permalink] ### Show Tags 02 Jun 2015, 08:13 1 An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool? (3/5) An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool? (3/5) of a pool/ 8 hours = 3/40 (the rate) (3 pools/40 hours) = (2/5* pool)/ x hours Cross multiply 3x = (2/5) 40 3x = (2/5) (8) (5) 3x = 16 x = 16/3 or 5 1/3 1/3 of an hour = 20 minutes * The pool is 3/5 full so 2/5 remains. (A) 5 hr 30 min (B) 5 hr 20 min (C) 4 hr 48 min (D) 3 hr 12 min (E) 2 hr 40 min Target Test Prep Representative Status: Head GMAT Instructor Affiliations: Target Test Prep Joined: 04 Mar 2011 Posts: 2830 Re: An empty pool being filled with water at a constant rate takes 8 hours [#permalink] ### Show Tags 17 May 2016, 16:01 1 1 Walkabout wrote: An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool? (A) 5 hr 30 min (B) 5 hr 20 min (C) 4 hr 48 min (D) 3 hr 12 min (E) 2 hr 40 min Solution: To solve we can setup a proportion. The proportion will read: A time of 8 hours is to filling up 3/5 of the pool is the same as a time of x number of hours is to filling up (the remaining) 2/5 of the pool. Setting this up mathematically we have: 8/(3/5) = x/(2/5) 8/(3/5) = x/(2/5) 40/3= 5x/2 Cross multiplying, we get: 80 = 15x 16 = 3x 16/3 = x 5 1/3 hours = x 5 hours and 20 minutes = x Answer: B _________________ Jeffery Miller Head of GMAT Instruction GMAT Quant Self-Study Course 500+ lessons 3000+ practice problems 800+ HD solutions Senior SC Moderator Joined: 22 May 2016 Posts: 2346 Re: An empty pool being filled with water at a constant rate takes 8 hours [#permalink] ### Show Tags 22 Oct 2017, 09:34 GMATD11 wrote: An empty pool being filled with water at a constant rate takes 8hours to fill to 3/5 of its capacity.how much more time will it take to finish filling the pool? A. 5hr 30min B. 5hr 20min C. 4hr 48min D. 3 hr 12min E. 2hr 40 min 45-second approach: Find rate of filling. Find work remaining. Find time needed to finish: Work divided by rate equals time (to fill volume that needs filling). What is rate of filling? $$\frac{Work}{time} = rate$$ RATE = $$\frac{(\frac{3}{5})}{8} = (\frac{3}{5}*\frac{1}{8})= \frac{3}{40}$$ How much work remaining? $$1 - (\frac{3}{5}) = (\frac{5}{5} - \frac{3}{5})= \frac{2}{5}$$ How much time to finish remaining work? $$\frac{Work}{rate} = time$$ Work remaining = $$\frac{2}{5}$$ Rate = $$\frac{3}{40}$$ $$\frac{(\frac{2}{5})}{(\frac{3}{40})}$$ = $$\frac{2}{5} * \frac{40}{3} = 5\frac{1}{3}hrs$$ Multiply any fraction of an hour by 60 to get minutes.* In cases where you already have the hours, and you need hours plus minutes, use only the fraction. (Do not include the 5 here.) $$\frac{1}{3}hr * 60 =$$ 20 minutes $$5\frac{1}{3}hrs$$ = 5 hours, 20 minutes Answer B *Because: $$\frac{1hr}{3} * \frac{60min}{1hr} =$$ 20 minutes, where hours cancel _________________ Never look down on anybody unless you're helping them up. --Jesse Jackson EMPOWERgmat Instructor Status: GMAT Assassin/Co-Founder Affiliations: EMPOWERgmat Joined: 19 Dec 2014 Posts: 13347 Location: United States (CA) GMAT 1: 800 Q51 V49 GRE 1: Q170 V170 Re: An empty pool being filled with water at a constant rate takes 8 hours [#permalink] ### Show Tags 20 Feb 2018, 15:05 Hi All, We're told that 8 hours fills 3/5 of the pool; the question asks how long it will take to fill the remaining 2/5 of the pool. Since the pool is filling at a constant rate, we can use a ratio to answer the question. The ratio can be written in a number of different ways; I used: 8/X = (3/5)/(2/5) Simplifying, we get… 8/X = 3/2 Now, cross-multiply… 3X = 16 X = 5 1/3 hours 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!*****

CEO
Joined: 11 Sep 2015
Posts: 3334
Re: An empty pool being filled with water at a constant rate takes 8 hours  [#permalink]

### Show Tags

05 Mar 2018, 08:31
Top Contributor
An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?

(A) 5 hr 30 min
(B) 5 hr 20 min
(C) 4 hr 48 min
(D) 3 hr 12 min
(E) 2 hr 40 min

Here's another approach:

IMPORTANT CONCEPT: After 8 hours, 3/5 of the job is finished and 2/5 of the job is remaining.
This means the remaining part of the job is 2/3 the size of the first part of the job.

Think of it this way:
If the pool had a capacity of 5 gallons, then the first part of the job would be filling 3 gallons, and the remaining part of the job is filling 2 gallons.
So, the remaining part of the job (filling 2 gallons) is 2/3 the size of the first part of the job (filling 3 gallons)

So, if it takes 8 hours to do the first part of the job, then the time to do the remaining part = 2/3 of 8 hours
2/3 of 8 hours = 2/3 x 8 hours
= 16/3 hours
= 5 1/3 hours
= 5 hours 20 minutes

Cheers,
Brent
_________________

Test confidently with gmatprepnow.com

Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 4547
Location: United States (CA)
Re: An empty pool being filled with water at a constant rate takes 8 hours  [#permalink]

### Show Tags

06 Mar 2018, 07:06
GMATD11 wrote:
An empty pool being filled with water at a constant rate takes 8hours to fill to 3/5 of its capacity.how much more time will it take to finish filling the pool?

A. 5hr 30min
B. 5hr 20min
C. 4hr 48min
D. 3 hr 12min
E. 2hr 40 min

We can let n = the time it takes to fill the remaining 2/5 of the pool and create the proportion:

8/(3/5) = n/(2/5)

40/3 = 5n/2

80 = 15n

n = 80/15 = 16/3 = 5 1/3 hours = 5 hours and 20 minutes

_________________

Scott Woodbury-Stewart
Founder and CEO

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

Director
Status: No dream is too large, no dreamer is too small
Joined: 14 Jul 2010
Posts: 516
Re: An empty pool being filled with water at a constant rate takes 8 hours  [#permalink]

### Show Tags

24 Oct 2018, 07:13
Top Contributor
3/5 full in 8 hours (rest = 1-(3/5) = 2/5)
2/5 is filled in (8*5*20)/3*5 = 8 hour 20 minutes
_________________

Collections:-
PSof OG solved by GC members: http://gmatclub.com/forum/collection-ps-with-solution-from-gmatclub-110005.html
DS of OG solved by GC members: http://gmatclub.com/forum/collection-ds-with-solution-from-gmatclub-110004.html
100 GMAT PREP Quantitative collection http://gmatclub.com/forum/gmat-prep-problem-collections-114358.html
Collections of work/rate problems with solutions http://gmatclub.com/forum/collections-of-work-rate-problem-with-solutions-118919.html
Mixture problems in a file with best solutions: http://gmatclub.com/forum/mixture-problems-with-best-and-easy-solutions-all-together-124644.html

Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4330
Location: India
GPA: 3.5
Re: An empty pool being filled with water at a constant rate takes 8 hours  [#permalink]

### Show Tags

24 Oct 2018, 08:08
Bunuel wrote:
An empty pool being filled with water at a constant rate takes 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?

(A) 5 hr 30 min
(B) 5 hr 20 min
(C) 4 hr 48 min
(D) 3 hr 12 min
(E) 2 hr 40 min

Let the capacity of the pool be $$40$$ Units ( LCM of 5 & 8)

So, in 8 Hours the pipe fills $$24$$ units; Thus efficiency of the pipe is 3units/Hour

Time required to fill the entire pool is $$\frac{16}{3}$$ hours = $$5\frac{1}{3} = 5 Hours 20 Min$$; Answer must be (B)
_________________

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: An empty pool being filled with water at a constant rate takes 8 hours &nbs [#permalink] 24 Oct 2018, 08:08
Display posts from previous: Sort by