GMAT Changed on April 16th - Read about the latest changes here

 It is currently 25 May 2018, 20:43

### 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

# An empty pool being filled with water at a constant rate tak

Author Message
TAGS:

### Hide Tags

Manager
Joined: 10 Nov 2010
Posts: 223
Location: India
Concentration: Strategy, Operations
GMAT 1: 520 Q42 V19
GMAT 2: 540 Q44 V21
WE: Information Technology (Computer Software)
An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

07 Feb 2011, 01:20
5
This post was
BOOKMARKED
00:00

Difficulty:

5% (low)

Question Stats:

78% (01:03) correct 22% (00:49) wrong based on 818 sessions

### HideShow timer Statistics

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

_________________

The proof of understanding is the ability to explain it.

Math Forum Moderator
Joined: 20 Dec 2010
Posts: 1902

### Show Tags

07 Feb 2011, 01:27
2
KUDOS
3/5 pool -> 8 hours
1 pool -> 8/(3/5) h
1 pool -> 40/3 h

So, it takes 40/3 hours to fill the entire pool but 8 hours out of 40/3 are already spent.

40/3 = 8 + x
x = (40/3) - 8 = 16/3 hours left to fill the entire pool

16/3 hours = 5hours 20minutes

Ans: "B"
_________________
Math Expert
Joined: 02 Sep 2009
Posts: 45423

### Show Tags

07 Feb 2011, 03:44
2
KUDOS
Expert's post
1
This post was
BOOKMARKED
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

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

To fill 3/5 of the pool took 8 hours --> to fill 2/5 of the pool will take 8/(3/5)*2/5=16/3 hours = 5 hours 20 minutes (because if t is the time needed to fill the pool then t*3/5=8 --> t=8*5/3 hours --> to fill 2/5 of the pool 8*5/3*2/5=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 = job/rate = 2/(3/8) = 16/3 hours = 5 hours 20 minutes.

_________________
Manager
Joined: 10 Nov 2010
Posts: 223
Location: India
Concentration: Strategy, Operations
GMAT 1: 520 Q42 V19
GMAT 2: 540 Q44 V21
WE: Information Technology (Computer Software)

### Show Tags

08 Feb 2011, 06:32
Bunuel wrote:
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

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

To fill 3/5 of the pool took 8 hours --> to fill 2/5 of the pool will take 8/(3/5)*2/5=16/3 hours = 5 hours 20 minutes (because if t is the time needed to fill the pool then t*3/5=8 --> t=8*5/3 hours --> to fill 2/5 of the pool 8*5/3*2/5=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 = job/rate = 2/(3/8) = 16/3 hours = 5 hours 20 minutes.

Thanks Bunuel
using this capacity left to fill in solution i can save time
_________________

The proof of understanding is the ability to explain it.

Current Student
Joined: 26 May 2005
Posts: 533

### Show Tags

Updated on: 11 Jun 2011, 00:08
6
KUDOS
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 11 Jun 2011, 00:05.
Last edited by sudhir18n on 11 Jun 2011, 00:08, edited 2 times in total.
Manager
Joined: 08 Sep 2010
Posts: 138

### Show Tags

11 Jun 2011, 10:47
2
KUDOS
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.

Math Expert
Joined: 02 Sep 2009
Posts: 45423
Re: An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

30 May 2013, 05:10
Expert's post
1
This post was
BOOKMARKED
Bumping for review and further discussion*. Get a kudos point for an alternative solution!

*New project from GMAT Club!!! Check HERE

All DS work/rate problems to practice: search.php?search_id=tag&tag_id=46
All PS work/rate problems to practice: search.php?search_id=tag&tag_id=66

_________________
Intern
Joined: 30 May 2013
Posts: 15
GMAT 1: 680 Q48 V35
Re: An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

05 Jun 2013, 15:04
1
KUDOS
I did this a little differently.
It takes 480 mins to fill 3/5 of the pool.
We're trying to find out how long it'll take for the remaining 2/5.
I solved how many minutes it'll take to fill the pool to 1/5 capacity and multiplied it by 2.
480 / 3 = 160 mins (1/5 full)
160 * 2 = 320 mins (2/5 full)
320 mins = 5 hours 20 mins
Manager
Joined: 17 Mar 2014
Posts: 214
An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

28 Jan 2017, 11:24
Bunuel wrote:
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

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

To fill 3/5 of the pool took 8 hours --> to fill 2/5 of the pool will take 8/(3/5)*2/5=16/3 hours = 5 hours 20 minutes (because if t is the time needed to fill the pool then t*3/5=8 --> t=8*5/3 hours --> to fill 2/5 of the pool 8*5/3*2/5=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 = job/rate = 2/(3/8) = 16/3 hours = 5 hours 20 minutes.

it took 8 hours to fill 3/5 of pool. Can't we consider it would have taken 2 hours to fill 1/5th of pool as rate is constant. so it will take 4hours to fill remaining 2/5th of pool ?
Math Expert
Joined: 02 Sep 2009
Posts: 45423
Re: An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

28 Jan 2017, 11:29
ammuseeru wrote:
Bunuel wrote:
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

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

To fill 3/5 of the pool took 8 hours --> to fill 2/5 of the pool will take 8/(3/5)*2/5=16/3 hours = 5 hours 20 minutes (because if t is the time needed to fill the pool then t*3/5=8 --> t=8*5/3 hours --> to fill 2/5 of the pool 8*5/3*2/5=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 = job/rate = 2/(3/8) = 16/3 hours = 5 hours 20 minutes.

it took 8 hours to fill 3/5 of pool. Can't we consider it would have taken 2 hours to fill 1/5th of pool as rate is constant. so it will take 4hours to fill remaining 2/5th of pool ?

HOW did you get this?

8 hours to fill 3/5 of pool
So, to fill 1/5th of the pool it'll take 3 times less, so 8/3 hours. Therefore to fill 2/5th it'll take twice as much time, so 16/3 hours.
_________________
Manager
Joined: 30 Apr 2013
Posts: 90
Re: An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

22 Oct 2017, 05:09
Lets assume tank capacity is 100 ml

So 8 hrs ----for 3/5*100 =60 ml
x hrs------40 ml

So ....8/60 = x/40

x= 5.30

where am i going wrong here?
Math Expert
Joined: 02 Sep 2009
Posts: 45423
Re: An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

22 Oct 2017, 05:49
santro789 wrote:
Lets assume tank capacity is 100 ml

So 8 hrs ----for 3/5*100 =60 ml
x hrs------40 ml

So ....8/60 = x/40

x= 5.30

where am i going wrong here?

Check arithmetic:

8/60 = x/40

x = 16/3.
_________________
Manager
Joined: 30 Apr 2013
Posts: 90
Re: An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

22 Oct 2017, 06:21
thanks Bunuel but 16/3 =5.33 which would be equal to 5.30 then how come the answer is 5.20
Math Expert
Joined: 02 Sep 2009
Posts: 45423
Re: An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

22 Oct 2017, 06:30
santro789 wrote:
thanks Bunuel but 16/3 =5.33 which would be equal to 5.30 then how come the answer is 5.20

1/3rd of an hour is 20 minutes.
_________________
SC Moderator
Joined: 22 May 2016
Posts: 1676
An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

22 Oct 2017, 10:34
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

*Because:

$$\frac{1hr}{3} * \frac{60min}{1hr} =$$ 20 minutes, where hours cancel

_________________

In the depths of winter, I finally learned
that within me there lay an invincible summer.

Study Buddy Forum Moderator
Joined: 04 Sep 2016
Posts: 968
Location: India
WE: Engineering (Other)
Re: An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

28 Dec 2017, 07:12
Bunuel, niks18, amanvermagmat

How valid is this approach?
x = full capacity

Amount of work = Rate * no of hours
(3/5)*x = R1 *8 (first phase)
(2/5) *x = R2 * y (remaining phase/ capacity to fill)

Setting proportionality:

8/(3x/5) = y/(2x/5)

I am skipping extra steps since led to same answer choice, ie y = 16/3
_________________

It's the journey that brings us happiness not the destination.

Director
Joined: 09 Mar 2016
Posts: 537
Re: An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

28 Dec 2017, 10:53
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

Whats wrong with my solution ?

8 = 3/5
x=2/5 cross multiply... but in the end I get 16/3 = 5,333
Math Expert
Joined: 02 Sep 2009
Posts: 45423
Re: An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

28 Dec 2017, 10:58
1
KUDOS
Expert's post
dave13 wrote:
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

Whats wrong with my solution ?

8 = 3/5
x=2/5 cross multiply... but in the end I get 16/3 = 5,333

Not sure what you are doing there but the answer you are getting is correct: 16/3 hours = 5 hours 20 minutes. This is explained in the solutions which are presented in this topic. It seems that you don't read the thread at all...
_________________
EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 11670
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: 340 Q170 V170
Re: An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

20 Feb 2018, 16:05
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

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!***********************

Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 2638
Location: United States (CA)
Re: An empty pool being filled with water at a constant rate tak [#permalink]

### Show Tags

06 Mar 2018, 08:06
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

Re: An empty pool being filled with water at a constant rate tak   [#permalink] 06 Mar 2018, 08:06
Display posts from previous: Sort by

# An empty pool being filled with water at a constant rate tak

 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®.