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 GRE 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.
Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
Your score will improve and your results will be more realistic
Is there something wrong with our timer?Let us know!
Target Test Prep GRE course is a unique, comprehensive online quant course that combines innovative software with time-tested study methods to prepare you for the rigors of the GRE. Offer valid until May 31
Strategy is a key aspect in acing the GRE exam - a single mistake could lead to an undesirable outcome. Attend this advanced session conducted by one of our strategy experts Piyush Beriwala, where he'll help you decode the GRE algorithm
GRE Math Challenge #26-Pump A can empty a pool in 8 minutes
[#permalink]
06 Nov 2015, 19:26
1
1
Expert Reply
4
Bookmarks
00:00
Question Stats:
53% (02:03) correct
46% (02:00) wrong based on 26 sessions
HideShow
timer Statistics
Pump A can empty a pool in 8 minutes.Pump B can empty a pool in 6 minutes.Pump A pumps the pool for 2 minutes before pump B joins in.How may minutes will it take to empty the pool together?
Re: GRE Math Challenge #26-Pump A can empty a pool in 8 minutes
[#permalink]
24 Aug 2016, 05:56
3
Expert Reply
1
Bookmarks
sandy wrote:
Pump A can empty a pool in 8 minutes.Pump B can empty a pool in 6 minutes.Pump A pumps the pool for 2 minutes before pump B joins in.How may minutes will it take to empty the pool together?
Let's assign a nice value for the volume of the pool and go from there.
Pump A can empty a pool in 8 minutes.Pump B can empty a pool in 6 minutes. The least common multiple of 8 and 6 is 24. So, let's say that the TOTAL volume of the pool is 24 gallons.
If pump A can empty a pool in 8 minutes, then pump A's rate = 24 gallons/8 minutes = 3 gallons per minute If pump B can empty a pool in 6 minutes, then pump B's rate = 24 gallons/6 minutes = 4 gallons per minute So, there COMBINED rate = 3 + 4 = 7 gallons per minute
Pump A pumps the pool for 2 minutes before pump B joins in.How may minutes will it take to empty the pool together? First 2 minutes: At a rate of 3 gallons per minute, pump A removes 6 gallons from the pool, which means the amount REMAINING in the pool = 24 - 6 = 18 gallons
At a COMBINED rate of 7 gallons per minute, the time it takes to remove the remaining 18 gallons = 18/7 minutes
So, the TOTAL TIME it takes to empty the pool = 2 minutes (pump A alone) + 18/7 minutes (together) = 32/7 minutes
Re: GRE Math Challenge #26-Pump A can empty a pool in 8 minutes
[#permalink]
28 Jul 2017, 03:12
1
Hi Brent, I did the same calculations that you did, but at the end of the problem I subtracted 2 minutes from 4.57 minutes because during those two minutes the machines were not working together. I was confused by the wording of the question since it asked for the time it took for the machines to empty the pool together, so I thought the answer would be 2.57 minutes. Will the questions on the GRE be phrased like this as well? Amy
Re: GRE Math Challenge #26-Pump A can empty a pool in 8 minutes
[#permalink]
28 Jul 2017, 05:16
1
Expert Reply
AmyK wrote:
Hi Brent, I did the same calculations that you did, but at the end of the problem I subtracted 2 minutes from 4.57 minutes because during those two minutes the machines were not working together. I was confused by the wording of the question since it asked for the time it took for the machines to empty the pool together, so I thought the answer would be 2.57 minutes. Will the questions on the GRE be phrased like this as well? Amy
I have a feeling, the test-makers would add some extra information to prevent ambiguity. Perhaps something like...
Pump A can empty a pool in 8 minutes. Pump B can empty a pool in 6 minutes. At 1:00pm Pump A starts pumping the pool. At 1:02pm, pump B joins in. At what time with the pool be empty?
_________________
Re: GRE Math Challenge #26-Pump A can empty a pool in 8 minutes
[#permalink]
25 Dec 2017, 05:30
sandy wrote:
Pump A can empty a pool in 8 minutes.Pump B can empty a pool in 6 minutes.Pump A pumps the pool for 2 minutes before pump B joins in.How may minutes will it take to empty the pool together?
can you check the answer, since the stem says empty the pool together, I thought the answer is 18/7?
Re: GRE Math Challenge #26-Pump A can empty a pool in 8 minutes
[#permalink]
13 Mar 2021, 06:44
Hello from the GRE Prep Club BumpBot!
Thanks to another GRE Prep 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.