Last visit was: 18 Jul 2025, 15:14 It is currently 18 Jul 2025, 15:14
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
User avatar
Jcpenny
Joined: 10 Oct 2008
Last visit: 12 Dec 2008
Posts: 46
Own Kudos:
441
 [141]
Posts: 46
Kudos: 441
 [141]
3
Kudos
Add Kudos
138
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
KarishmaB
Joined: 16 Oct 2010
Last visit: 18 Jul 2025
Posts: 16,111
Own Kudos:
74,393
 [30]
Given Kudos: 475
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,111
Kudos: 74,393
 [30]
15
Kudos
Add Kudos
15
Bookmarks
Bookmark this Post
User avatar
Ashishmathew01081987
Joined: 20 Jan 2013
Last visit: 07 Jun 2020
Posts: 93
Own Kudos:
304
 [14]
Given Kudos: 71
Status:I am not a product of my circumstances. I am a product of my decisions
Location: India
Concentration: Operations, General Management
GPA: 3.92
WE:Operations (Energy)
Posts: 93
Kudos: 304
 [14]
8
Kudos
Add Kudos
6
Bookmarks
Bookmark this Post
User avatar
BrentGMATPrepNow
User avatar
Major Poster
Joined: 12 Sep 2015
Last visit: 13 May 2024
Posts: 6,755
Own Kudos:
34,126
 [6]
Given Kudos: 799
Location: Canada
Expert
Expert reply
Posts: 6,755
Kudos: 34,126
 [6]
6
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Jcpenny
A pump started filling an empty pool with water and continued at a constant rate until the pool was full. At noon the pool was 1/3 full, and \(1\frac{1}{4}\) hours later it was 3/4 full. What was the total number of hours that it took the pump to fill the pool?

A. \(2\frac{1}{3}\)
B. \(2\frac{2}{3}\)
C. 3
D. \(3\frac{1}{2}\)
E. \(3\frac{2}{3}\)

For this type of question, I like to assign a "nice value" to the job.

In this case we're looking for a number that works well with 1/3, 3/4 and even 1 1/4
So, let's say the pool has a capacity of 60 liters.

At noon the pool was 1/3 full, . . .
1/3 of 60 liters = 20 liters
So, at 12:00pm, the pool contained 20 liters of water

. . . and 1 1/4 hours later it was 3/4 full.
1 1/4 hours = 1.25 hours = 75 minutes.
3/4 of 60 liters = 45 liters
So, at 1:15pm, the pool contained 45 liters of water

What was the total number of hours that it took the pump to fill the pool?
45 liters - 20 liters = 25 liters
So, in 1.25 hours, 25 liters of water was added to the pool

Rate = output/time
So, the rate at which water is added to the pool = (25 liters)/(1.25 hours) = 20 liters per hour

Time = output/rate
So, at a rate of 20 liters per hour, the time it takes to fill the 60 liter pool = 60/20 liters = 3 hours

Answer: C
General Discussion
User avatar
alpha_plus_gamma
Joined: 14 Aug 2007
Last visit: 17 Jun 2010
Posts: 298
Own Kudos:
621
 [7]
Concentration: MC, PE, VC
 Q50  V37
Posts: 298
Kudos: 621
 [7]
3
Kudos
Add Kudos
4
Bookmarks
Bookmark this Post
Jcpenny
A pump started filling an empty pool with water and continued at
a constant rate until the pool was full. At noon the pool was 1/3 full,
and 1+1/4 hours later it was 3/4 full. What was the total number of
hours that it took the pump to fill the pool?
A. 2+1/3 B. 2+2/3 C. 3
D. 3+1/2 E. 3+2/3

in 1+1/4 =5/4 hrs the pump filled 3/4-1/3 = 5/12th of the pool
in 1 hr it fills 1/3 of the pool
so in 3 hrs it will fill the entire pool.
avatar
nevermoreflow
Joined: 02 Dec 2012
Last visit: 08 Oct 2014
Posts: 33
Own Kudos:
4
 [3]
GMAT Date: 01-01-2014
Posts: 33
Kudos: 4
 [3]
3
Kudos
Add Kudos
Bookmarks
Bookmark this Post
alpha_plus_gamma
Jcpenny
A pump started filling an empty pool with water and continued at
a constant rate until the pool was full. At noon the pool was 1/3 full,
and 1+1/4 hours later it was 3/4 full. What was the total number of
hours that it took the pump to fill the pool?
A. 2+1/3 B. 2+2/3 C. 3
D. 3+1/2 E. 3+2/3

in 1+1/4 =5/4 hrs the pump filled 3/4-1/3 = 5/12th of the pool
in 1 hr it fills 1/3 of the pool
so in 3 hrs it will fill the entire pool.

I was with you up until 5/12th of the pool. How did you get the in 1 hour it fills 1/3 of the poor?
avatar
OptimusPrepJanielle
Joined: 06 Nov 2014
Last visit: 08 Sep 2017
Posts: 1,779
Own Kudos:
1,447
 [4]
Given Kudos: 23
Expert
Expert reply
Posts: 1,779
Kudos: 1,447
 [4]
2
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
A pump started filling an empty pool with water and continued at a constant rate until the pool was full. At noon the pool was 1/3 full, and 1 1/4 hours later it was 3/4 full. What was the total number of hours that it took the pump to fill the pool?

(3/4) - (1/3) = 5/12. 5/12 of the pool was full in 1 1/4 hours time (5/4 hours). To determine a rate of filling we divide how much is full by the time. That is (5/12) ÷ (5/4) = 1/3. This means it fills a pool in 3 hours.

A. 2 1/3
B. 2 2/3
C. 3
D. 3 1/2
E. 3 2/3
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
at noon or 12:00PM it is filled 1/3 of total, say x = 1/3x
1hour 15 mins later it is 3/4x filled
so amount it filled in 75mins = (3/4)x - (1/3)x
=> 15*12 mins => 3 hours
C is the answer
User avatar
Nunuboy1994
Joined: 12 Nov 2016
Last visit: 24 Apr 2019
Posts: 559
Own Kudos:
Given Kudos: 167
Location: United States
Schools: Yale '18
GMAT 1: 650 Q43 V37
GRE 1: Q157 V158
GPA: 2.66
Schools: Yale '18
GMAT 1: 650 Q43 V37
GRE 1: Q157 V158
Posts: 559
Kudos: 122
Kudos
Add Kudos
Bookmarks
Bookmark this Post
OptimusPrepJanielle
A pump started filling an empty pool with water and continued at a constant rate until the pool was full. At noon the pool was 1/3 full, and 1 1/4 hours later it was 3/4 full. What was the total number of hours that it took the pump to fill the pool?

(3/4) - (1/3) = 5/12. 5/12 of the pool was full in 1 1/4 hours time (5/4 hours). To determine a rate of filling we divide how much is full by the time. That is (5/12) ÷ (5/4) = 1/3. This means it fills a pool in 3 hours.

A. 2 1/3
B. 2 2/3
C. 3
D. 3 1/2
E. 3 2/3

I got as far as finding 5/12- though where are you getting 3 hours? Is it the reciprocal of 1/3?
User avatar
KrishnakumarKA1
Joined: 05 Jan 2017
Last visit: 13 Oct 2020
Posts: 403
Own Kudos:
Given Kudos: 15
Location: India
Posts: 403
Kudos: 302
Kudos
Add Kudos
Bookmarks
Bookmark this Post
let the total volume be x and rate of flow be r

3x/4 - x/3 = r *5/4
or 5x/12 = r*5/4
or x = r*3

therefre in three hours, the pool will be filled
User avatar
JeffTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 04 Mar 2011
Last visit: 05 Jan 2024
Posts: 2,996
Own Kudos:
7,951
 [5]
Given Kudos: 1,646
Status:Head GMAT Instructor
Affiliations: Target Test Prep
Expert
Expert reply
Posts: 2,996
Kudos: 7,951
 [5]
4
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
Jcpenny
A pump started filling an empty pool with water and continued at a constant rate until the pool was full. At noon the pool was 1/3 full, and \(1\frac{1}{4}\) hours later it was 3/4 full. What was the total number of hours that it took the pump to fill the pool?

A. \(2\frac{1}{3}\)
B. \(2\frac{2}{3}\)
C. 3
D. \(3\frac{1}{2}\)
E. \(3\frac{2}{3}\)

Since it took 1¼ = 5/4 hours to fill 3/4 - 1/3 = 9/12 - 4/12 = 5/12 of the pool, we can let x = the number of hours to fill the pool and create a proportion to determine how long it will take to fill the entire pool.

(5/4)/(5/12) = x/1

5/4 = 5x/12

60 = 20x

x = 3

Answer: C
avatar
john133
Joined: 30 Jul 2017
Last visit: 19 May 2018
Posts: 1
Own Kudos:
2
 [2]
Given Kudos: 2
Posts: 1
Kudos: 2
 [2]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
VeritasPrepKarishma
Jcpenny
A pump started filling an empty pool with water and continued at
a constant rate until the pool was full. At noon the pool was 1/3 full,
and 1+1/4 hours later it was 3/4 full. What was the total number of
hours that it took the pump to fill the pool?
A. 2+1/3 B. 2+2/3 C. 3
D. 3+1/2 E. 3+2/3



The time elapsed between 1/3 full pool and 3/4 full pool is 5/4 hrs. This means 3/4 - 1/3 = 5/12 of the pool was filled in 5/4 hrs.

Again, (5/12)th of the pool will be filled in 5/4 hrs

1 pool will be filled in \(\frac{5/4}{5/12} * 1 = 3\) hrs

Hi Karishma,

I was able to follow till the last portion. Can you clarify why we are able to divide the time by rate to figure out how long it will take to fill 1 pool? I was able to solve this correctly however I am looking for a faster way to solve these type of problems.

Thanks!
User avatar
bebs
Joined: 18 Jun 2018
Last visit: 03 Dec 2021
Posts: 331
Own Kudos:
207
 [1]
Given Kudos: 1,283
Concentration: Finance, Healthcare
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
We have only one variable (volume of the pool) so let us assume the volume of the pool is 12 liters

At noon, the pool is 4 L (1/3 x 12 L) full, we do not know the time it took to fill 4 L of the pool at this point

At 1:15 pm (75 mins later), the pool is 9 L (3/4 x 12 L) full =====> Rate = (9 - 4) L/75 mins = 1/15 L/min

Therefore, it took 60 mins (4 L x 15 L/min) to fill the 4 L at noon

Time it took to fill the remaining 3 L (remember we assumed the pool is 12 L?) is 45 mins (3 L * 15 L/min)

Therefore, the total time it took to fill the pool = 60 + 75 + 45 = 180 minutes = 3 hours (Answer choice C)


Jcpenny
A pump started filling an empty pool with water and continued at a constant rate until the pool was full. At noon the pool was 1/3 full, and \(1\frac{1}{4}\) hours later it was 3/4 full. What was the total number of hours that it took the pump to fill the pool?

A. \(2\frac{1}{3}\)
B. \(2\frac{2}{3}\)
C. 3
D. \(3\frac{1}{2}\)
E. \(3\frac{2}{3}\)
avatar
lstsch
Joined: 09 Aug 2018
Last visit: 10 Apr 2020
Posts: 9
Own Kudos:
Given Kudos: 134
Posts: 9
Kudos: 3
Kudos
Add Kudos
Bookmarks
Bookmark this Post
chetan2u VeritasKarishma

Hello - Why we are able to divide the time by rate to figure out how long it will take to fill 1 pool? "(5/4)/(5/12)∗1=3 hrs"
I thought the formula to calculate the time is: Time = Work/Rate but that gives me 1/3. Thank you very much in advance!
User avatar
KarishmaB
Joined: 16 Oct 2010
Last visit: 18 Jul 2025
Posts: 16,111
Own Kudos:
74,393
 [3]
Given Kudos: 475
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,111
Kudos: 74,393
 [3]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
lstsch
chetan2u VeritasKarishma

Hello - Why we are able to divide the time by rate to figure out how long it will take to fill 1 pool? "(5/4)/(5/12)∗1=3 hrs"
I thought the formula to calculate the time is: Time = Work/Rate but that gives me 1/3. Thank you very much in advance!


"The time elapsed between 1/3 full pool and 3/4 full pool is 5/4 hrs. This means 3/4 - 1/3 = 5/12 of the pool was filled in 5/4 hrs.

Again, (5/12)th of the pool will be filled in 5/4 hrs"


I am guessing you understand this part. Rest is all application the formula Work = Rate*Time only. Here is how:

(5/12)th of the pool (this is amount of work done - amount of pool filled) will be filled in (5/4) hrs (this is time taken for this work done)

So constant RATE of filling pool = Work / Time = (5/12) / (5/4)

Now, this is the constant rate. We want the time taken to fill 1 pool (work to be done is 1)

Time taken to fill 1 pool = Work / Rate = 1 / ((5/12) / (5/4) = (5/4) / (5/12)

Note what is the work done and time taken in each case. You have been given time taken (5/4 hrs) for certain amount of work (5/12th pool) first. You use this to get the rate of filling. Then you use the rate to find the time taken to do a different amount of work (1 pool). So you apply the formula twice.

In my explanation, I have simply used the direct variation between work and time to get the answer. Knowing that rate is constant, I say:

A amount of work is done in time T.
B amount of work will be done in (T/A)*B

e.g. 1/2 work is done in 2 hrs
1 full work will be done in 2/(1/2) * 1 = 4 hrs
If work doubles, time taken doubles too.
User avatar
Kinshook
User avatar
Major Poster
Joined: 03 Jun 2019
Last visit: 18 Jul 2025
Posts: 5,702
Own Kudos:
5,236
 [2]
Given Kudos: 161
Location: India
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Products:
GMAT 1: 690 Q50 V34
Posts: 5,702
Kudos: 5,236
 [2]
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
Jcpenny
A pump started filling an empty pool with water and continued at a constant rate until the pool was full. At noon the pool was 1/3 full, and \(1\frac{1}{4}\) hours later it was 3/4 full. What was the total number of hours that it took the pump to fill the pool?

A. \(2\frac{1}{3}\)
B. \(2\frac{2}{3}\)
C. 3
D. \(3\frac{1}{2}\)
E. \(3\frac{2}{3}\)

Given:
1. A pump started filling an empty pool with water and continued at a constant rate until the pool was full.
2. At noon the pool was 1/3 full, and \(1\frac{1}{4}\) hours later it was 3/4 full.

Asked: What was the total number of hours that it took the pump to fill the pool?

At 1200 hrs, the pool was 1/3 full
\(1\frac{1}{4}\) hours later it was 3/4 full.

In 5/4 hours, pump fills = 3/4 - 1/3 = (9-4)/12 = 5/12 of the pool
In 1 hour, pump fills = 5*4/5*12 = 1/3 of the pool

Number of hours required to fill the pool = 3 hours

IMO C
User avatar
Archit3110
User avatar
Major Poster
Joined: 18 Aug 2017
Last visit: 18 Jul 2025
Posts: 8,351
Own Kudos:
Given Kudos: 243
Status:You learn more from failure than from success.
Location: India
Concentration: Sustainability, Marketing
GMAT Focus 1: 545 Q79 V79 DI73
GPA: 4
WE:Marketing (Energy)
GMAT Focus 1: 545 Q79 V79 DI73
Posts: 8,351
Kudos: 4,833
Kudos
Add Kudos
Bookmarks
Bookmark this Post
let total capacity by 12
noon filling done is 4 units
1.25 hrs later 9 units
rate per hour is
(9-4) ; 5 units

time 5/4 hrs
rate 5*4/5 ; 4 units per hr

3 units will be filled in 3/4 ; .75 hrs
total time 1+.25+.75
3 hrs
OPTION C

Jcpenny
A pump started filling an empty pool with water and continued at a constant rate until the pool was full. At noon the pool was 1/3 full, and \(1\frac{1}{4}\) hours later it was 3/4 full. What was the total number of hours that it took the pump to fill the pool?

A. \(2\frac{1}{3}\)
B. \(2\frac{2}{3}\)
C. 3
D. \(3\frac{1}{2}\)
E. \(3\frac{2}{3}\)
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 37,454
Own Kudos:
Posts: 37,454
Kudos: 1,013
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Moderators:
Math Expert
102619 posts
PS Forum Moderator
698 posts