Summer is Coming! Join the Game of Timers Competition to Win Epic Prizes. Registration is Open. Game starts Mon July 1st.

It is currently 15 Jul 2019, 23:23

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

Confirm Cancel

Working alone at its constant rate, pump x pumped out 1/3 of the water

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

Hide Tags

Find Similar Topics 
Manager
Manager
avatar
S
Joined: 12 Mar 2015
Posts: 54
Location: United States
GMAT 1: 670 Q45 V38
GPA: 2.99
WE: Corporate Finance (Aerospace and Defense)
GMAT ToolKit User
Working alone at its constant rate, pump x pumped out 1/3 of the water  [#permalink]

Show Tags

New post 22 Jan 2017, 14:57
7
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

84% (02:05) correct 16% (02:18) wrong based on 249 sessions

HideShow timer Statistics


Working alone at its constant rate, pump x pumped out 1/3 of the water in a pool in 4 hours. Then pump Y started working and the two pumps, working simultaneously at their respective constant rates, pumped out the rest of the water in 6 hours. How many hours would it have taken pump Y, working alone at its constant rate, to pump out all the water that was pumped out of the pool?

A: 18
B: 24
C: 36
D: 48
E: 52
Most Helpful Expert Reply
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7764
Re: Working alone at its constant rate, pump x pumped out 1/3 of the water  [#permalink]

Show Tags

New post 22 Jan 2017, 16:13
5
3
alandizzle wrote:
Working alone at its constant rate, pump x pumped out 1/3 of the water in a pool in 4 hours. Then pump Y started working and the two pumps, working simultaneously at their respective constant rates, pumped out the rest of the water in 6 hours. How many hours would it have taken pump Y, working alone at its constant rate, to pump out all the water that was pumped out of the pool?

I'm having a tough time with this question, can someone help me break it down? I guessed correctly but not sure how to get there within 2 minutes.

A: 18
B: 24
C: 36
D: 48
E: 52


Hi

Three steps that will get you to answer..
1) time of pump x..
1/3 in 4 hrs, so complete in 4*3=12 hrs

2) combined time of x and y..
(1-1/3) or 2/3 in 6 hrs, so complete in 6*3/2=9 hrs..

3) finally our answer or pump y..
1/(combined time) - 1/(time of pump x)= 1/9-1/12=1/36..
So 36hrs

Hope it helps
_________________
General Discussion
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 56234
Re: Working alone at its constant rate, pump x pumped out 1/3 of the water  [#permalink]

Show Tags

New post 23 Jan 2017, 01:16
2
alandizzle wrote:
Working alone at its constant rate, pump x pumped out 1/3 of the water in a pool in 4 hours. Then pump Y started working and the two pumps, working simultaneously at their respective constant rates, pumped out the rest of the water in 6 hours. How many hours would it have taken pump Y, working alone at its constant rate, to pump out all the water that was pumped out of the pool?

I'm having a tough time with this question, can someone help me break it down? I guessed correctly but not sure how to get there within 2 minutes.

A: 18
B: 24
C: 36
D: 48
E: 52


Very similar questions to practice:
working-at-constant-rate-pump-x-pumped-out-half-of-the-water-in-a-flo-223089.html
working-alone-at-its-constant-rate-pump-x-pumped-out-of-the-water-216023.html
_________________
Manager
Manager
avatar
S
Joined: 12 Mar 2015
Posts: 54
Location: United States
GMAT 1: 670 Q45 V38
GPA: 2.99
WE: Corporate Finance (Aerospace and Defense)
GMAT ToolKit User
Re: Working alone at its constant rate, pump x pumped out 1/3 of the water  [#permalink]

Show Tags

New post 23 Jan 2017, 12:12
Bunuel wrote:
alandizzle wrote:
Working alone at its constant rate, pump x pumped out 1/3 of the water in a pool in 4 hours. Then pump Y started working and the two pumps, working simultaneously at their respective constant rates, pumped out the rest of the water in 6 hours. How many hours would it have taken pump Y, working alone at its constant rate, to pump out all the water that was pumped out of the pool?

I'm having a tough time with this question, can someone help me break it down? I guessed correctly but not sure how to get there within 2 minutes.

A: 18
B: 24
C: 36
D: 48
E: 52


Very similar questions to practice:
working-at-constant-rate-pump-x-pumped-out-half-of-the-water-in-a-flo-223089.html
working-alone-at-its-constant-rate-pump-x-pumped-out-of-the-water-216023.html


Thank you Bunuel! You are such an amazing help!
VP
VP
avatar
P
Joined: 07 Dec 2014
Posts: 1206
Re: Working alone at its constant rate, pump x pumped out 1/3 of the water  [#permalink]

Show Tags

New post 23 Jan 2017, 12:40
1
Working alone at its constant rate, pump x pumped out 1/3 of the water in a pool in 4 hours. Then pump Y started working and the two pumps, working simultaneously at their respective constant rates, pumped out the rest of the water in 6 hours. How many hours would it have taken pump Y, working alone at its constant rate, to pump out all the water that was pumped out of the pool?

A: 18
B: 24
C: 36
D: 48
E: 52

rate of x=1/12
rate of x and y=1/9
rate of y=1/9-1/12=1/36
36 hours
C
Target Test Prep Representative
User avatar
D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 6923
Location: United States (CA)
Re: Working alone at its constant rate, pump x pumped out 1/3 of the water  [#permalink]

Show Tags

New post 25 Jan 2017, 10:16
3
3
alandizzle wrote:
Working alone at its constant rate, pump x pumped out 1/3 of the water in a pool in 4 hours. Then pump Y started working and the two pumps, working simultaneously at their respective constant rates, pumped out the rest of the water in 6 hours. How many hours would it have taken pump Y, working alone at its constant rate, to pump out all the water that was pumped out of the pool?

A: 18
B: 24
C: 36
D: 48
E: 52


We are given that pump X pumped out 1/3 of the water in a pool in 4 hours. Since rate = work/time, the rate of pump X is (1/3)/4 = 1/12. Also, since 1/3 of the water was pumped out of the pool, 2/3 was left to be removed.

Since pump X and Y pumped out 2/3 of the water in 6 hours, the combined rate of pumps X and Y is (2/3)/6 = 2/18 = 1/9.

Finally, since rate of pump X + rate of pump Y = the combined rate of pumps X and Y, the rate of pump Y is:

1/9 - 1/12 = 4/36 - 3/36 = 1/36

Thus, pump Y can pump all the water out of the pool in 36 hours.

Answer: C
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Manager
Manager
avatar
S
Joined: 13 Dec 2013
Posts: 150
Location: United States (NY)
Concentration: General Management, International Business
Schools: Cambridge"19 (A)
GMAT 1: 710 Q46 V41
GMAT 2: 720 Q48 V40
GPA: 4
WE: Consulting (Consulting)
Reviews Badge
Re: Working alone at its constant rate, pump x pumped out 1/3 of the water  [#permalink]

Show Tags

New post 14 Apr 2017, 14:03
alandizzle wrote:
Working alone at its constant rate, pump x pumped out 1/3 of the water in a pool in 4 hours. Then pump Y started working and the two pumps, working simultaneously at their respective constant rates, pumped out the rest of the water in 6 hours. How many hours would it have taken pump Y, working alone at its constant rate, to pump out all the water that was pumped out of the pool?

I'm having a tough time with this question, can someone help me break it down? I guessed correctly but not sure how to get there within 2 minutes.

A: 18
B: 24
C: 36
D: 48
E: 52


1/X (amount of work done by X in 1h)= (1/3)/4=1/12
Now, there are 2/3 of work left to be done.
(1/X)+(1/Y)=(2/3)/6
(1/12)+(1/Y)=1/9
(1/Y)=(12/108)-(9/108)=3/108=1/36
Time = reciprocal of rate (work done in one hour) = 36h. C
Intern
Intern
avatar
B
Joined: 26 Jul 2017
Posts: 6
Location: Pakistan
Concentration: Strategy, Organizational Behavior
Schools: IMD '21 (S)
GPA: 2.25
WE: Consulting (Consulting)
Re: Working alone at its constant rate, pump x pumped out 1/3 of the water  [#permalink]

Show Tags

New post 04 Sep 2018, 06:21
We can also use the percentage method to solve this question

we know that pump A did 1/3 of work in 4 hours, which means that 1/12 or 8.33% of work was done by pump A in one hour.

Now 2/3 or 66.6% of work is left. This work was done by pump A and B in 6 Hours. which means that 11.1% work was done in 1 hour. Of the 11.1% work 8.33% was done by A and 11.1 - 8.33 = 2.67% of work was done by Pump B.

If we round 2.67 to 3 It will take pump B 33.3 hours to do the work. The closest is 36 which is the answer.

Thanks
Manager
Manager
avatar
S
Joined: 26 Jan 2016
Posts: 78
CAT Tests
Re: Working alone at its constant rate, pump x pumped out 1/3 of the water  [#permalink]

Show Tags

New post 20 Apr 2019, 11:42
2
Say pool contains 12l of of water (multiple of 3 and 4 for ease of calculation)

Then X pumped out 1/3= 4l in 4 hours, speed of X = 1l/hr

Then Y joined X and both took 6 hours to take out restof water which is 12-4(pumped out by X) = 8l

X working at is constant speed of 1l/hr took out 6l and remaining 2l was pumped out by Y in 6hrs.
So speed of Y= 2/6l/he

Y working alone to take out 12l of water at above speed would take 12/(2/6)= 36 hrs.

Please share correct answer.

Posted from my mobile device
_________________
Thanks,
Priyanka

Please give +1 kudos if the post helps..!!
Senior Manager
Senior Manager
User avatar
V
Joined: 15 Jan 2018
Posts: 422
Concentration: General Management, Finance
GMAT 1: 720 Q50 V37
Premium Member Reviews Badge
Re: Working alone at its constant rate, pump x pumped out 1/3 of the water  [#permalink]

Show Tags

New post 20 Apr 2019, 12:34
Simple formula based question that must be complete in 1-1.5 min. Make sure to write your work on the paper, and follow the steps.

Given,
Pump X pumped out 1/3 of the water in a pool in 4 hours. Therefore, the pump will take 12 hours to completely empty the pool.
Pumps X and Y pumped out 2/3 of the water in a pool in 6 hours. Therefore, both pumps will take 9 hours to completely empty the pool.

From the above two statements, we can calculate that Pump Y alone will take 36 hours to completely empty the pool.

Therefore, the correct answer is answer choice C. 36

Important Formula
If Pump/Pipe X can fill a tank in A hours and Pumps/Pipes X and Y can together fill it in B hours, then Pump/Pipe Y alone can fill the tank in AB/(A-B)

_________________
New to GMAT Club or overwhelmed with so many resources? Follow the GMAT Club Study Plan!
Not happy with your GMAT score? Retaking GMAT Strategies!

Game of Timers - Join the Competition to Win Prizes
Image
GMAT Club Bot
Re: Working alone at its constant rate, pump x pumped out 1/3 of the water   [#permalink] 20 Apr 2019, 12:34
Display posts from previous: Sort by

Working alone at its constant rate, pump x pumped out 1/3 of the water

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





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne