NEW HERE? LEARN MORE
closeclose
Last visit was: 24 Apr 2024, 08:58 It is currently 24 Apr 2024, 08:58
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

Working at constant rate, pump X pumped out half of the water in a flo

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
avatar
pravinpillai2015
Intern
Intern
Joined: 23 Dec 2015
Posts: 1
Own Kudos [?]: 44 [44]
Given Kudos: 10
Send PM
Working at constant rate, pump X pumped out half of the water in a flo [#permalink] New post   Updated on: 02 Aug 2016, 00:17
6
Kudos
37
Bookmarks
00:00
A
B
C
D
E

Difficulty:

15% (low)

Question Stats:

84% (01:44) correct 16% (01:59) wrong based on 707 sessions
Hide Show timer Statistics
Working at constant rate, pump X pumped out half of the water in a flooded basement in 4 hours. The pump Y was started and the two pumps, working independently at their respective constant rates, pumped out rest of the water in 3 hours. How many hours would it have taken pump Y , operating alone at its own constant rate, to pump out all of the water that was pumped out of the basement?

a. 10
b. 12
c. 14
d. 18
e. 24
ShowHide Answer
Official Answer
E

Originally posted by pravinpillai2015 on 01 Aug 2016, 21:06.
Last edited by Bunuel on 02 Aug 2016, 00:17, edited 1 time in total.
RENAMED THE TOPIC.
Most Helpful Reply
User avatar
P
gracie
VP
VP
Joined: 07 Dec 2014
Posts: 1072
Own Kudos [?]: 1561 [15]
Given Kudos: 27
Send PM
Working at constant rate, pump X pumped out half of the water in a flo [#permalink] New post   02 Aug 2016, 12:33
11
Kudos
4
Bookmarks
rate of x=1/8
rate of x+y=1/6
rate of y=1/6-1/8=1/24
24 hours
avatar
mahfuz_fahim
Intern
Intern
Joined: 04 May 2015
Posts: 2
Own Kudos [?]: 5 [5]
Given Kudos: 8
Send PM
Re: Working at constant rate, pump X pumped out half of the water in a flo [#permalink] New post   01 Aug 2016, 23:35
4
Kudos
1
Bookmarks
Here pump x was able to work 1/2 the job in 4 hrs.

so it would have taken the pump x to complete the task in 8 hrs. so 1/x=1/8.....eqn(1)

again x and y working independently doing the same work (1/2 of the work) take 3hrs.
so total task would take 6 hrs. 1/x+1/y=1/6.........eqn(2)

solve eqn 1 and eqn 2 to get y=24
General Discussion
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92902
Own Kudos [?]: 618763 [2]
Given Kudos: 81587
Send PM
CAT Tests Forum Quiz Mode
Working at constant rate, pump X pumped out half of the water in a flo [#permalink] New post   02 Aug 2016, 00:19
2
Kudos
Expert Reply
pravinpillai2015 wrote:
Working at constant rate, pump X pumped out half of the water in a flooded basement in 4 hours. The pump Y was started and the two pumps, working independently at their respective constant rates, pumped out rest of the water in 3 hours. How many hours would it have taken pump Y , operating alone at its own constant rate, to pump out all of the water that was pumped out of the basement?

a. 10
b. 12
c. 14
d. 18
e. 24




Almost the same question to practice: https://gmatclub.com/forum/working-alon ... 16023.html

Hope it helps.
User avatar
L
pushpitkc
Senior PS Moderator
Joined: 26 Feb 2016
Posts: 2873
Own Kudos [?]: 5205 [1]
Given Kudos: 47
Location: India
GPA: 3.12
Send PM
Re: Working at constant rate, pump X pumped out half of the water in a flo [#permalink] New post   21 Jan 2018, 13:01
1
Bookmarks
pravinpillai2015 wrote:
Working at constant rate, pump X pumped out half of the water in a flooded basement in 4 hours. The pump Y was started and the two pumps, working independently at their respective constant rates, pumped out rest of the water in 3 hours. How many hours would it have taken pump Y , operating alone at its own constant rate, to pump out all of the water that was pumped out of the basement?

a. 10
b. 12
c. 14
d. 18
e. 24



If the pump X pumped out half the water in 4 hours, it will pump out the entire water in 8 hours.
Similarly, the pump Y was started and the two pumps operating together are able to pump out
the entire water in 3 hours.

Assume the total capacity of the pump to be 96 units.

So, the pump X must be pumping out 12 units/hour. Since, both the pumps working together
pump out the remainder of the water in 3 hours, their combined capacity will be 16 units/hour.
Hence, pump Y must be pumping out 4 units/hour.

Therefore, Pump Y alone will take \(\frac{96}{4}\) = 24 hours(Option E)
avatar
B
Nived
Intern
Intern
Joined: 30 Nov 2017
Posts: 19
Own Kudos [?]: 23 [1]
Given Kudos: 12
Send PM
Re: Working at constant rate, pump X pumped out half of the water in a flo [#permalink] New post   15 Feb 2018, 09:56
1
Kudos
Suppose X extracts x liters/hour, while Y extracts y liters/hour
In 4 hours, X extracts 4 x liters
This is half of the basement capacity. So, total volume of water in the basement = 8x liters

After 4 hours, Y was started as well. They flush the remaining 4 x in 3 hours.

In 3 hours, X and Y combined would flush 3*(x + y)

It is given that 3*(x + y) = 4x
This gives x = 3y

Operating alone how much would Y take?

Total water = 8x
Y's capacity = y liters/hour

So, time taken by Y = 8x/y

We know x = 3y
So, x/y = 3

So, time taken by Y = 8x/y = 8*3 = 24
avatar
B
gulyaa
Intern
Intern
Joined: 28 Aug 2016
Posts: 6
Own Kudos [?]: 12 [0]
Given Kudos: 98
Send PM
Reviews Badge
Re: Working at constant rate, pump X pumped out half of the water in a flo [#permalink] New post   22 Apr 2019, 15:34
pravinpillai2015 wrote:
Working at constant rate, pump X pumped out half of the water in a flooded basement in 4 hours. The pump Y was started and the two pumps, working independently at their respective constant rates, pumped out rest of the water in 3 hours. How many hours would it have taken pump Y , operating alone at its own constant rate, to pump out all of the water that was pumped out of the basement?

a. 10
b. 12
c. 14
d. 18
e. 24


Trying plugging:

We are looking at half capacities throughout the problem, so we could half the answer choices for simplicity. If X = 4h -> rate = 1/4; X + Y = 3h -> rate = 1/3. We can start plugging answer choices from B:


B: 12 -> 6 h -> 1/6 + 1/4 = 5/12 - almost 1/2 or too big for the 1/3 we need, that means we need a smaller Y rate or higher Y hours
D: 18 -> 9 h -> 1/9 + 1/4 = 13/36 - if we compare with 1/3 or 13/39, 13/ 36 is still a bit big, but closer to what we need -> answer E
User avatar
P
hero_with_1000_faces
Senior Manager
Senior Manager
Joined: 02 Jan 2016
Status:Studying 4Gmat
Posts: 366
Own Kudos [?]: 96 [0]
Given Kudos: 314
Location: India
Concentration: Strategy, Entrepreneurship
Schools: Darden '22 Marshall '22 AGSM '23
GMAT 1: 590 Q37 V33
GPA: 4
WE:Law (Manufacturing)
Send PM
Reviews Badge
Re: Working at constant rate, pump X pumped out half of the water in a flo [#permalink] New post   12 Jan 2021, 22:01
A alternative approach:

We can infer that x takes 8 hours to remove water completely, now:

We see that X worked 7 hours - 4+3 hours, and was left with only one hours of work.

For that 1 hour of work Y took 3 hours, so for 8 hours of X's work Y will take 8*3 = 24 hours
User avatar
B
kritisachan
Intern
Intern
Joined: 10 Jun 2021
Posts: 13
Own Kudos [?]: 12 [1]
Given Kudos: 41
Location: India
Send PM
Working at constant rate, pump X pumped out half of the water in a flo [#permalink] New post   21 Jun 2023, 03:09
1
Kudos
pump x was able to do 1/2 of the job in 4 hrs
pump x would do the entire work alone in 1/8 hrs
therefore, 1/x = 1/8 --- eqn (1)

since x and y are now working together, they finish the entire thing in 3 hrs
total time taken would be 6 hrs

pump x + pump y = 1/x + 1/y= 1/6 ---- eqn (2)

1/8+ 1/y = 1/6
1/y = 1/6- 1/8
1/y = 8-6/48
1/y = 1/24

therefore, y = 24
GMAT Club Bot
gmatclubot
Working at constant rate, pump X pumped out half of the water in a flo [#permalink]
21 Jun 2023, 03:09
Moderators:
Bunuel
Math Expert
92902 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions