Oct 20 07:00 AM PDT  09:00 AM PDT Get personalized insights on how to achieve your Target Quant Score. Oct 22 09:00 AM PDT  10:00 AM PDT Watch & learn the Do's and Don’ts for your upcoming interview Oct 22 08:00 PM PDT  09:00 PM PDT On Demand for $79. For a score of 4951 (from current actual score of 40+) AllInOne Standard & 700+ Level Questions (150 questions) Oct 23 08:00 AM PDT  09:00 AM PDT Join an exclusive interview with the people behind the test. If you're taking the GMAT, this is a webinar you cannot afford to miss! Oct 26 07:00 AM PDT  09:00 AM PDT Want to score 90 percentile or higher on GMAT CR? Attend this free webinar to learn how to prethink assumptions and solve the most challenging questions in less than 2 minutes. Oct 27 07:00 AM EDT  09:00 AM PDT Exclusive offer! Get 400+ Practice Questions, 25 Video lessons and 6+ Webinars for FREE. Oct 27 08:00 PM EDT  09:00 PM EDT Strategies and techniques for approaching featured GMAT topics. One hour of live, online instruction
Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 58434

Working together, Rafael and Salvador can tabulate a certain set of da
[#permalink]
Show Tags
03 Aug 2018, 10:35
Question Stats:
72% (01:35) correct 28% (02:02) wrong based on 682 sessions
HideShow timer Statistics
Working together, Rafael and Salvador can tabulate a certain set of data in 2 hours. In how many hours can Rafael tabulate the data working alone? (1) Working alone, Rafael can tabulate the data in 3 hours less time than Salvador, working alone, can tabulate the data. (2) Working alone, Rafael can tabulate the data in 1/2 the time that Salvador, working alone, can tabulate the data. NEW question from GMAT® Quantitative Review 2019 (DS13907)
Official Answer and Stats are available only to registered users. Register/ Login.
_________________




VP
Status: Learning stage
Joined: 01 Oct 2017
Posts: 1013
WE: Supply Chain Management (Energy and Utilities)

Re: Working together, Rafael and Salvador can tabulate a certain set of da
[#permalink]
Show Tags
03 Aug 2018, 13:39
Bunuel wrote: Working together, Rafael and Salvador can tabulate a certain set of data in 2 hours. In how many hours can Rafael tabulate the data working alone? (1) Working alone, Rafael can tabulate the data in 3 hours less time than Salvador, working alone, can tabulate the data. (2) Working alone, Rafael can tabulate the data in 1/2 the time that Salvador, working alone, can tabulate the data. NEW question from GMAT® Quantitative Review 2019 (DS13907) Let 'r' and 's' are the no of hours taken by Rafael & Salvador, working alone, to complete the job respectively. Given, \(\frac{1}{r}+\frac{1}{s}=\frac{1}{2}\)(1) Question stem: r=? St1: Working alone, Rafael can tabulate the data in 3 hours less time than Salvador, working alone, can tabulate the data.Or, r=s3 Or, s=r+3 from(1), we have, \(\frac{1}{r}+\frac{1}{s}=\frac{1}{2}\) Now substituting, \(\frac{1}{r}+\frac{1}{(r+3)}=\frac{1}{2}\) Or, \(r^2r6=0\) Or, (r+2)(r3)=0 Or, r=3 Sufficient. St2: Working alone, Rafael can tabulate the data in 1/2 the time that Salvador, working alone, can tabulate the data.Or, \(r=\frac{s}{2}\) Or, \(s=2r\) from(1), we have, \(\frac{1}{r}+\frac{1}{s}=\frac{1}{2}\) Now substituting, \(\frac{1}{r}+\frac{1}{2r}=\frac{1}{2}\) Or, 2r=6 Or, r=3 Sufficient. Ans. (D)
_________________
Regards,
PKN
Rise above the storm, you will find the sunshine




Intern
Joined: 09 Jan 2019
Posts: 2

Re: Working together, Rafael and Salvador can tabulate a certain set of da
[#permalink]
Show Tags
02 Feb 2019, 09:07
How did you transform \(\frac{1}{(r+3)}+\frac{1}{r}=\frac{1}{2}\) into \(r^2r6=0\) ? PKN



VP
Status: Learning stage
Joined: 01 Oct 2017
Posts: 1013
WE: Supply Chain Management (Energy and Utilities)

Re: Working together, Rafael and Salvador can tabulate a certain set of da
[#permalink]
Show Tags
02 Feb 2019, 09:34
redwood wrote: How did you transform \(\frac{1}{(r+3)}+\frac{1}{r}=\frac{1}{2}\) into \(r^2r6=0\) ? PKN Hi redwood, You must know the addition and subtraction of fractional expressions. Here, \(\frac{1}{(r+3)}+\frac{1}{r}=\frac{1}{2}\) Or, \(\frac{[1*r+1*(r+3)]}{(r+3)r}=\frac{1}{2}\) Or, \(\frac{(2r+3)}{(r^2+3r)}=\frac{1}{2}\) Crossmultiplying, We have \(2(2r+3)=r^2+3r\) Or, \(4r+6=r^2+3r\) Or, \(r^2r6=0\) Hope it helps.
_________________
Regards,
PKN
Rise above the storm, you will find the sunshine



Intern
Joined: 09 Jan 2019
Posts: 2

Re: Working together, Rafael and Salvador can tabulate a certain set of da
[#permalink]
Show Tags
02 Feb 2019, 11:07
PKN Thanks a lot, got it now!



Intern
Joined: 14 Sep 2018
Posts: 11

Re: Working together, Rafael and Salvador can tabulate a certain set of da
[#permalink]
Show Tags
02 Feb 2019, 13:59
Thanks. OG had a very confusing explanation. This is quite clear, and straightforward to follow.



Target Test Prep Representative
Status: Chief Curriculum and Content Architect
Affiliations: Target Test Prep
Joined: 24 Nov 2014
Posts: 618

Re: Working together, Rafael and Salvador can tabulate a certain set of da
[#permalink]
Show Tags
05 Feb 2019, 10:37
Bunuel wrote: Working together, Rafael and Salvador can tabulate a certain set of data in 2 hours. In how many hours can Rafael tabulate the data working alone?
(1) Working alone, Rafael can tabulate the data in 3 hours less time than Salvador, working alone, can tabulate the data. (2) Working alone, Rafael can tabulate the data in 1/2 the time that Salvador, working alone, can tabulate the data.
Information given: Working together, Rafael and Salvador can tabulate a certain set of data in 2 hours. Question: In how many hours can Rafael tabulate the data working alone? This question may seem complicated, but the truth is that since we know how long it takes for the two of them to complete the job, if we have any information that we can use to accurately compare how fast one works to how fast the other works, then we can answer the question. Statement 1: Working alone, Rafael can tabulate the data in 3 hours less time than Salvador, working alone, can tabulate the data. We do not need to use any math to determine whether this statement is sufficient. We have only to notice that we know how long it takes for both of them to do the work together and that we have information that we can use to determine their relative speeds. With that information, we could work our way to the answer to the question, how many hours Rafael would take to do the job alone. To see why, consider this: Time for Rafael to do the job = R Time for Salvador to do the job = R + 3 We are now working with one variable, and we have the time it takes for them to do the job together. So, we could work our way to Rafael's time. Sufficient. Statement 2: Working alone, Rafael can tabulate the data in 1/2 the time that Salvador, working alone, can tabulate the data. This tells us that Rafael works twice as fast as Salvador works. Since we know how long they take to do the job together, we can clearly work our way to Rafael's speed and then his time to do the job himself. To see why, consider this: Rafael's speed = 1/r Salvador's speed = 1/2r We are now working with one variable, and we have the time it takes for them to do the job together. So, we could work our way to Rafael's time, but we won't because this is a DS question. Sufficient. The correct answer is D.
_________________
5star 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.



Intern
Joined: 04 Jun 2014
Posts: 15

Re: Working together, Rafael and Salvador can tabulate a certain set of da
[#permalink]
Show Tags
28 Mar 2019, 07:57
Hi Marty, I've solved this with similar logic and didn't solve the equation. Although, I knew that this equation will come out to be a quadratic which might have both imaginary roots or 2 positive roots. So, my question is about the assumption that Gmat will give a true scenario in statements which will for sure have one positive root only that will be an answer. Thus, we don't need to check if the equation has only 1 positive root. Please, let me know if this assumption is wrong. Regards, Pankaj MartyTargetTestPrep wrote: Bunuel wrote: Working together, Rafael and Salvador can tabulate a certain set of data in 2 hours. In how many hours can Rafael tabulate the data working alone?
(1) Working alone, Rafael can tabulate the data in 3 hours less time than Salvador, working alone, can tabulate the data. (2) Working alone, Rafael can tabulate the data in 1/2 the time that Salvador, working alone, can tabulate the data.
Information given: Working together, Rafael and Salvador can tabulate a certain set of data in 2 hours. Question: In how many hours can Rafael tabulate the data working alone? This question may seem complicated, but the truth is that since we know how long it takes for the two of them to complete the job, if we have any information that we can use to accurately compare how fast one works to how fast the other works, then we can answer the question. Statement 1: Working alone, Rafael can tabulate the data in 3 hours less time than Salvador, working alone, can tabulate the data. We do not need to use any math to determine whether this statement is sufficient. We have only to notice that we know how long it takes for both of them to do the work together and that we have information that we can use to determine their relative speeds. With that information, we could work our way to the answer to the question, how many hours Rafael would take to do the job alone. To see why, consider this: Time for Rafael to do the job = R Time for Salvador to do the job = R + 3 We are now working with one variable, and we have the time it takes for them to do the job together. So, we could work our way to Rafael's time. Sufficient. Statement 2: Working alone, Rafael can tabulate the data in 1/2 the time that Salvador, working alone, can tabulate the data. This tells us that Rafael works twice as fast as Salvador works. Since we know how long they take to do the job together, we can clearly work our way to Rafael's speed and then his time to do the job himself. To see why, consider this: Rafael's speed = 1/r Salvador's speed = 1/2r We are now working with one variable, and we have the time it takes for them to do the job together. So, we could work our way to Rafael's time, but we won't because this is a DS question. Sufficient. The correct answer is D.



Target Test Prep Representative
Status: Chief Curriculum and Content Architect
Affiliations: Target Test Prep
Joined: 24 Nov 2014
Posts: 618

Working together, Rafael and Salvador can tabulate a certain set of da
[#permalink]
Show Tags
28 Mar 2019, 08:46
pankajpaliitkgp wrote: Hi Marty,
I've solved this with similar logic and didn't solve the equation. Although, I knew that this equation will come out to be a quadratic which might have both imaginary roots or 2 positive roots. So, my question is about the assumption that Gmat will give a true scenario in statements which will for sure have one positive root only that will be an answer. Thus, we don't need to check if the equation has only 1 positive root. Please, let me know if this assumption is wrong.
Regards, Pankaj Hi Pahkaj. If a problem Solving question could be solved via the use of a quadratic, the solution will have only one root that works. Of course, Problem Solving questions have to work that way. Otherwise, they would not make sense, as a problem solving question has to have only one correct answer. However, in answering a Data Sufficiency question, you can't assume that there will be only one root that works. It could be that there are multiple roots that work and that a statement or both statements are, therefore, insufficient.
_________________
5star 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.




Working together, Rafael and Salvador can tabulate a certain set of da
[#permalink]
28 Mar 2019, 08:46






