It is currently 20 Nov 2017, 12:36

### 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

# M12-10

Author Message
SVP
Joined: 04 May 2006
Posts: 1878

Kudos [?]: 1443 [1], given: 1

Schools: CBS, Kellogg

### Show Tags

14 May 2008, 03:17
1
KUDOS
3
This post was
BOOKMARKED
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

With both valves open, the pool will be filled with water in 48 minutes. The first valve alone would fill the pool in 2 hours. What is the capacity of the pool if every minute the second valve admits 50 cubic meters of water more than the first?

(A) 9000 cubic meters
(B) 10500 cubic meters
(C) 11750 cubic meters
(D) 12000 cubic meters
(E) 12500 cubic meters

[Reveal] Spoiler: OA
D

Source: GMAT Club Tests - hardest GMAT questions

I sweated when time gone!
_________________

Kudos [?]: 1443 [1], given: 1

Manager
Joined: 27 Jul 2007
Posts: 112

Kudos [?]: 10 [0], given: 0

### Show Tags

14 May 2008, 04:00
I get D

let x mcube be the vol

then
60*x/(x+3000) = 48
=> x = 12000

Kudos [?]: 10 [0], given: 0

Manager
Joined: 10 Mar 2008
Posts: 67

Kudos [?]: 36 [5], given: 0

### Show Tags

15 May 2008, 03:45
5
KUDOS
1
This post was
BOOKMARKED
sondenso wrote:
With both valves open, the pool will be filled with water in 48 minutes. The first valve alone would fill the pool in 2 hours. What is the capacity of the pool if every minute the second valve admits 50 cubic meters of water more than the first?

9000 cubic meters
10500 cubic meters
11750 cubic meters
12000 cubic meters
12500 cubic meters

I sweated when time gone!

let first taps speed be x cu/min
then second taps speed be x+50 cu/min
then
48(x+(x+50))= total capacity---------(1)

since first tap can fill in 2 hrs
60*2(x) is total capacity------------(2)

equating
x=100

total capacity=100*2*60 =12000

hope this is clear

Kudos [?]: 36 [5], given: 0

Retired Moderator
Joined: 18 Jul 2008
Posts: 960

Kudos [?]: 303 [1], given: 5

### Show Tags

04 Feb 2009, 17:17
1
KUDOS
I'm confused here:

Shouldn't we add the quantity of valve1 + quantity of valve2 = total quantity? Please tell me where I'm going wrong.

For example:

This is what I did:

1. Figure out the time Valve 2 took to fill the pool by itself

1/Valve1 + 1/Valve2 = 1/48
1/120 mins (or 2 hours) + 1/Valve2 = 1/48 mins
Valve2 = 80 mins

2. Find the Quantity to fill the pool X

120(X) + 80 (X+50) = 48 (2x + 50)

So this is where it goes down hill...
not sure why we don't include 80 (X+50) in the equation?

Kudos [?]: 303 [1], given: 5

Senior Manager
Joined: 30 Nov 2008
Posts: 483

Kudos [?]: 367 [2], given: 15

Schools: Fuqua

### Show Tags

05 Feb 2009, 09:18
2
KUDOS
I'm confused here:

Shouldn't we add the quantity of valve1 + quantity of valve2 = total quantity? Please tell me where I'm going wrong.

For example:

This is what I did:

1. Figure out the time Valve 2 took to fill the pool by itself

1/Valve1 + 1/Valve2 = 1/48
1/120 mins (or 2 hours) + 1/Valve2 = 1/48 mins
Valve2 = 80 mins

2. Find the Quantity to fill the pool X

120(X) + 80 (X+50) = 48 (2x + 50)

So this is where it goes down hill...
not sure why we don't include 80 (X+50) in the equation?

Step 1 is correct in that you found that Valve 2 can fill a tank in 80 min.

Step 2 is wrong.

Valve 1 can fill the tank in 120 Min with x being the volume filled per min - So total volume = 120*x ----> Eq1
Valve 2 can fill the tank in 80 min with (x+50) being the volume filled per min. So the total volume = 80(x+50) ---> Eq2

Together can fill the tank in 48 min with (x + (x + 5)) being the volume filled per min. So the total volume = 48(x + (x + 5)) ---> Eq 3.

To solve for x, pick any of the 2 of the 3 eq, ie either equate Eq 1 = Eq 2 or Eq 1 = Eq 3 or Eq2 = Eq 3 and get the

ie 120X = 80(x + 50) ==> x = 100.

We get x = 100.

Now substitute value of x in any of the 3 eq and you should get the total volume.

Kudos [?]: 367 [2], given: 15

SVP
Joined: 07 Nov 2007
Posts: 1790

Kudos [?]: 1088 [2], given: 5

Location: New York

### Show Tags

05 Feb 2009, 09:57
2
KUDOS
1
This post was
BOOKMARKED
sondenso wrote:
rohit929 wrote:
sondenso wrote:
With both valves open, the pool will be filled with water in 48 minutes. The first valve alone would fill the pool in 2 hours. What is the capacity of the pool if every minute the second valve admits 50 cubic meters of water more than the first?

9000 cubic meters
10500 cubic meters
11750 cubic meters
12000 cubic meters
12500 cubic meters

I sweated when time gone!

let first taps speed be x cu/min
then second taps speed be x+50 cu/min
then
48(x+(x+50))= total capacity---------(1)

since first tap can fill in 2 hrs
60*2(x) is total capacity------------(2)

equating
x=100

total capacity=100*2*60 =12000

hope this is clear

So sooooooo great, rohit! Thanks! I lost many basic, I think. I approach this by using work rate = work/time. And stucked!

Indeed "rate = work/time" approach is same as rohit used.

capacity=work = rate*time = (x +x+50)*48
capacity= rate*time = x*120
_________________

Smiling wins more friends than frowning

Kudos [?]: 1088 [2], given: 5

Manager
Joined: 13 Aug 2009
Posts: 199

Kudos [?]: 128 [6], given: 16

Schools: Sloan '14 (S)

### Show Tags

16 Aug 2009, 10:12
6
KUDOS
Here is how I solved the problem:

9. With both valves open, the pool will be filled with water in 48 minutes. The first valve alone would fill the pool in 2 hours. What is the capacity of the pool if every minute the second valve admits 50 cubic meters of water more than the first?
* 9000 cubic meters
* 10500 cubic meters
* 11750 cubic meters
* 12000 cubic meters
* 12500 cubic meters

let B = # of mins for the second valve alone to fill the pool

1/(time it takes first valve to fill the pool) + 1/B = 1/(total time its takes to fill the pool)
1/120 + 1/B = 1/48
B = 80

let C = the capacity of the pool
C/80 - C/120 = 50
C = 12000

Kudos [?]: 128 [6], given: 16

Director
Joined: 01 Apr 2008
Posts: 872

Kudos [?]: 860 [0], given: 18

Name: Ronak Amin
Schools: IIM Lucknow (IPMX) - Class of 2014

### Show Tags

17 Aug 2009, 14:27
Here x and x+50 are nothing but the rates of the pipes.
R1 + R2 = R ( R=combined rate )

x+x+50 = Capacity/48, Now capacity = 120x
=> 2x+50 = 120x/48
=> x=100

Kudos [?]: 860 [0], given: 18

Intern
Joined: 15 Nov 2009
Posts: 31

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

Location: Moscow, Russia

### Show Tags

21 Jan 2010, 12:57
48 min = 0.8 hrs, then if x is pool's volume
both pipes open
for 0.8 hrs - x cubic m (multiply both sides by 5)
for 4 hrs - 5x cubic m
Within 4 hrs
the first pipe alone could fill 2 pools,
the second 3 pools.
So, the second could fill one pool more than the 1st being open for 4hrs.
x=4*60*50=12000 (D).

Last edited by nvgroshar on 26 Jan 2011, 11:03, edited 1 time in total.

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

Manager
Joined: 20 Oct 2009
Posts: 104

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

### Show Tags

23 Jan 2010, 23:18
It's actually an easy word question - just take your time to set up the x variable - let x be the amount of water in cube meter the first valve admits per minute, x+50 will be for the second valve

48(x+(x+50))=60*2x

=> x=100 substitute back to the right hand side of the equation =>
total capacity=100*120 =12,000

Usually when I have enough time, I put the x value in the left side to see if I get 12,000 as well - just for sanity check
_________________

Dream the impossible and do the incredible.

Live. Love. Laugh.

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

Manager
Joined: 26 Nov 2009
Posts: 162

Kudos [?]: 62 [0], given: 5

### Show Tags

25 Jan 2010, 07:18
from the given info we know that

1/x+1/y=48 ( both valve will fill in 48 mins)
1/x=1/120 (fist valve will fill in 2 hrs or 120 mins)

so by solving
1/y=1/80 (second valve will take 80 mins)

first valve =1/120
second valve =1/80

if the tank can be filled by first valve in 120 minutes and the second one by 80 mins

then answer should be exactly divided by 120 and 80 only choice D satisfies this criterion so I picked ans D ( of courseif it contains more than one choice divisble by 120 and 80 then you'll have to solve it precisely)

or you can solve this by solving for x tradionaly by applying formula as everyone stated above

1/120(x)+1/80(x+5)=1/48(2x+5)

Kudos [?]: 62 [0], given: 5

Manager
Joined: 16 Feb 2010
Posts: 218

Kudos [?]: 378 [0], given: 16

### Show Tags

28 Nov 2010, 14:39
 With both valves open, the pool will be filled with water in 48 minutes. The first valve alone would fill the pool in 2 hours. If the second valve emits 50 cubic meters of water more than the first every minute, then what is the capacity of the pool?(C) 2008 GMAT Club - m12#10 * 9000 cubic meters * 10500 cubic meters * 11750 cubic meters * 12000 cubic meters * 12500 cubic meters

still puzzled how to do it my way....

found out that the rate of V1 is 1/120 and V2 is 1/100....correct? if yes, then how to find volume?

thanks.....

Kudos [?]: 378 [0], given: 16

Math Expert
Joined: 02 Sep 2009
Posts: 42269

Kudos [?]: 132810 [3], given: 12378

### Show Tags

28 Nov 2010, 15:14
3
KUDOS
Expert's post
3
This post was
BOOKMARKED
zisis wrote:
 With both valves open, the pool will be filled with water in 48 minutes. The first valve alone would fill the pool in 2 hours. If the second valve emits 50 cubic meters of water more than the first every minute, then what is the capacity of the pool?(C) 2008 GMAT Club - m12#10 * 9000 cubic meters * 10500 cubic meters * 11750 cubic meters * 12000 cubic meters * 12500 cubic meters

still puzzled how to do it my way....

found out that the rate of V1 is 1/120 and V2 is 1/100....correct? if yes, then how to find volume?

thanks.....

Let the rate of the first valve be $$x$$ cubic meters per minute, then the rate of the second valve will be $$x+50$$ cubic meters per minute.

As both valves open fill the pool in 48 minutes then the capacity of the pool equals to $$C=time*combined \ rate=48(x+x+50)=48(2x+50)$$;
But as the first valve alone fills the pool in 2 hours (120 minutes) then the capacity of the pool also equals to $$C=time*rate=120x$$;

So, $$120x=48(2x+50)$$ --> $$x=100$$ --> $$C=120x=12,000$$.

Hope it's clear.
_________________

Kudos [?]: 132810 [3], given: 12378

Director
Status: No dream is too large, no dreamer is too small
Joined: 14 Jul 2010
Posts: 609

Kudos [?]: 1154 [0], given: 39

### Show Tags

25 Nov 2011, 06:16
Total Volume = x
First valve and second valve take 48 minutes to fill the pool
The both valves filled x/48 in 1 minute
First valve filled x/120 part in 1 minute
So, Second valve filled in 1 minute = x/48 - x/120 = 3x/240 part

Given that 3x/240 - x/120 = 50
x =12000
Ans. D.
_________________

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

Kudos [?]: 1154 [0], given: 39

Director
Joined: 28 Jul 2011
Posts: 518

Kudos [?]: 304 [0], given: 16

Location: United States
GPA: 3.86
WE: Accounting (Commercial Banking)

### Show Tags

25 Nov 2011, 20:18
good question..........and an amazing explanation
_________________

Kudos [?]: 304 [0], given: 16

Intern
Joined: 03 Dec 2011
Posts: 2

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

### Show Tags

03 Dec 2011, 07:59
Gurus,

With both valves open, the pool will be filled with water in 48 minutes. The first valve alone would fill the pool in 2 hours. What is the capacity of the pool if every minute the second valve admits 50 cubic meters of water more than the first?

(A) 9000 cubic meters
(B) 10500 cubic meters
(C) 11750 cubic meters
(D) 12000 cubic meters
(E) 12500 cubic meters

I tried this question and tried this approach but did not get me the answer? Please could you tell me what I did wrong?
W= RT
R=w/t
c/120 +x =C/48
X( rate at which second valve fills up) .I got stuck here cos i had two many unknowns

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

Intern
Joined: 20 Dec 2011
Posts: 18

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

### Show Tags

31 Jan 2012, 13:03
Jiggyjee1

X is C/120+50 which is given so only 1 unknown.

+1 D

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

Intern
Joined: 29 Jan 2013
Posts: 1

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

### Show Tags

30 Jan 2013, 06:28
We can use plugin approach also here.

From the options given, assume that capacity of tank is = 12000

Tap 1 fills 12000 in 2 hrs. In 1 min = 100 cu/m
Tap 2 in 1 min = 100 + 50 = 150.

So in 48 mins = 48(100 (t1) + 150 (t2) = 12000.

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

Manager
Joined: 23 Jan 2013
Posts: 172

Kudos [?]: 58 [0], given: 41

Concentration: Technology, Other
Schools: Haas
GMAT Date: 01-14-2015
WE: Information Technology (Computer Software)

### Show Tags

30 Jan 2013, 17:03
Consider the time the second pipe takes to fill the tank as 1/x = 1/48 - 1/120
= 1/80 .

therefore x takes 80 mins to fill the pipe . But since each minute pipe B fills in an extra 50 from A using a smart number 100
B takes = 80 * 150 = 12000 would be the capacity

Kudos [?]: 58 [0], given: 41

Manager
Joined: 04 Oct 2013
Posts: 161

Kudos [?]: 123 [0], given: 55

Location: India
GMAT Date: 05-23-2015
GPA: 3.45

### Show Tags

16 Jan 2014, 10:07
With both valves open, the pool will be filled with water in 48 minutes. The first valve alone would fill the pool in 2 hours. What is the capacity of the pool if every minute the second valve admits 50 cubic meters of water more than the first?

(A) 9000 cubic meters
(B) 10500 cubic meters
(C) 11750 cubic meters
(D) 12000 cubic meters
(E) 12500 cubic meters

Given:
First valve takes 120 mins to fill the pool
Both valve take 48 mins to fill the pool

Let capacity of pool be $$x$$ cubic meters
Inlet rate of First valve per minute $$= x/120$$
Combined inlet rate per minute of both valve $$= x/48$$

Inlet rate of second valve per minute :$$( x/48) - (x/120 ) = x/80$$

Since, every minute second valve admits 50 cubic meters of water more than the first valve,

$$(x/80) - (x/120) = 50$$
Or,$$x = 12000$$ cubic meters

Kudos [?]: 123 [0], given: 55

Re: M12-10   [#permalink] 16 Jan 2014, 10:07

Go to page    1   2    Next  [ 22 posts ]

Display posts from previous: Sort by

# M12-10

Moderator: Bunuel

 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®.