Last visit was: 13 Jun 2024, 22:52 It is currently 13 Jun 2024, 22:52
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
SORT BY:
Date
Tags:
Difficulty: Sub 505 Level,    Work and Rate Problems,                   
Show Tags
Hide Tags
Math Expert
Joined: 02 Sep 2009
Posts: 93696
Own Kudos [?]: 631587 [52]
Given Kudos: 82279
Send PM
Most Helpful Reply
Tutor
Joined: 28 Apr 2016
Posts: 40
Own Kudos [?]: 122 [21]
Given Kudos: 9
Location: United States
GMAT 1: 780 Q51 V47
GPA: 3.9
Send PM
e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3717
Own Kudos [?]: 17133 [11]
Given Kudos: 165
Send PM
General Discussion
Manager
Manager
Joined: 24 Jun 2013
Posts: 120
Own Kudos [?]: 327 [3]
Given Kudos: 124
Location: India
Schools: ISB '20 GMBA '20
GMAT 1: 680 Q47 V36
Send PM
Re: Machine R and machine S work at their respective constant rates. How [#permalink]
3
Kudos
Bunuel wrote:
Machine R and machine S work at their respective constant rates. How much time does it take machine R, working alone, to complete a certain job?

(1) The amount of time that it takes machine S, working alone, to complete the job is 34 the amount of time that it takes machine R, working alone, to complete the job.
(2) Machine R and machine S, working together, take 12 minutes to complete the job.


NEW question from GMAT® Official Guide 2019


(DS00858)


could you pls check the stat 1) , is it 34 the amount or 3/4th the amount or sumthin else , coz it is not clear the way it is stated
Math Expert
Joined: 02 Sep 2009
Posts: 93696
Own Kudos [?]: 631587 [1]
Given Kudos: 82279
Send PM
Re: Machine R and machine S work at their respective constant rates. How [#permalink]
1
Kudos
Expert Reply
doomedcat wrote:
Bunuel wrote:
Machine R and machine S work at their respective constant rates. How much time does it take machine R, working alone, to complete a certain job?

(1) The amount of time that it takes machine S, working alone, to complete the job is 34 the amount of time that it takes machine R, working alone, to complete the job.
(2) Machine R and machine S, working together, take 12 minutes to complete the job.


NEW question from GMAT® Official Guide 2019


(DS00858)


could you pls check the stat 1) , is it 34 the amount or 3/4th the amount or sumthin else , coz it is not clear the way it is stated

________________________
Thank you. Edited.
Manager
Manager
Joined: 24 Jun 2013
Posts: 120
Own Kudos [?]: 327 [3]
Given Kudos: 124
Location: India
Schools: ISB '20 GMBA '20
GMAT 1: 680 Q47 V36
Send PM
Re: Machine R and machine S work at their respective constant rates. How [#permalink]
3
Kudos
Bunuel wrote:
Machine R and machine S work at their respective constant rates. How much time does it take machine R, working alone, to complete a certain job?

(1) The amount of time that it takes machine S, working alone, to complete the job is 3/4 the amount of time that it takes machine R, working alone, to complete the job.
(2) Machine R and machine S, working together, take 12 minutes to complete the job.


NEW question from GMAT® Official Guide 2019


(DS00858)


let individual rates be R & S respectively, we need to find R

stat1 ) given that S = \(\frac{3}{4}\) R, but we do not more information to cal respective values , hence Not Suff

stat2) given together they both take 12 min , so lets put it the work time equation

\(\frac{1}{S}\)+\(\frac{1}{R}\) =\(1/12\) ==> \(\frac{R+X}{RS}\) = \(\frac{1}{12}\)

still not suff as we two unknowns and 1 eq

Stat1) + stat2) , we can use stat1) and put the value S in the eq of stat 2) , and we can cal R , Hence suff

C

Just for calculations, R= 28 mins

Originally posted by doomedcat on 24 Jun 2018, 23:22.
Last edited by doomedcat on 24 Jun 2018, 23:55, edited 1 time in total.
Manager
Manager
Joined: 11 Apr 2018
Posts: 100
Own Kudos [?]: 46 [3]
Given Kudos: 139
Location: India
GPA: 4
WE:Information Technology (Computer Software)
Send PM
Re: Machine R and machine S work at their respective constant rates. How [#permalink]
1
Kudos
1
Bookmarks
Let's assume R can do the work in r hrs. S can do the work in s hrs.
To find: s

From Statement 1:
\(r = \frac{3}{4} s\)
As, it is 2V 1E it is not solvable.
So, statement 1 is insufficient.

From Statement 2:
\(( \frac{1}{r} + \frac{1}{s}) \frac{12}{60} = 1\)
\(( \frac{1}{r} + \frac{1}{s}) = 5\)
As, it is 2V 1E it is not solvable.
So, statement 2 is insufficient.

From Statement 1 and Statement 2:
As we have 2V 2E we can solve it.
Hence, C is the correct answer.
Manager
Manager
Joined: 14 Jan 2017
Posts: 102
Own Kudos [?]: 130 [2]
Given Kudos: 119
Location: India
Send PM
Re: Machine R and machine S work at their respective constant rates. How [#permalink]
2
Kudos
Lowkya wrote:
Let's assume R can do the work in r hrs. S can do the work in s hrs.
To find: s

From Statement 1:
\(r = \frac{3}{4} s\)


Don't you think it should be
\(s = \frac{3}{4} r\)

Kind Regards!
GMAT Club Legend
GMAT Club Legend
Joined: 08 Jul 2010
Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator
Posts: 6012
Own Kudos [?]: 13613 [3]
Given Kudos: 124
Location: India
GMAT: QUANT+DI EXPERT
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
WE:Education (Education)
Send PM
Re: Machine R and machine S work at their respective constant rates. How [#permalink]
2
Kudos
1
Bookmarks
Expert Reply
Bunuel wrote:
Machine R and machine S work at their respective constant rates. How much time does it take machine R, working alone, to complete a certain job?

(1) The amount of time that it takes machine S, working alone, to complete the job is 3/4 the amount of time that it takes machine R, working alone, to complete the job.
(2) Machine R and machine S, working together, take 12 minutes to complete the job.


NEW question from GMAT® Official Guide 2019


(DS00858)


Wanna make solving the Official Questions interesting???


Click here and solve 1000+ Official Questions with Video solutions as Timed Sectional Tests
and Dedicated Data Sufficiency (DS) Course


Answer: Option C

Video solution by GMATinsight



Get TOPICWISE: Concept Videos | Practice Qns 100+ | Official Qns 50+ | 100% Video solution CLICK HERE.
Two MUST join YouTube channels : GMATinsight (1000+ FREE Videos) and GMATclub :)
Target Test Prep Representative
Joined: 14 Oct 2015
Status:Founder & CEO
Affiliations: Target Test Prep
Posts: 19013
Own Kudos [?]: 22400 [0]
Given Kudos: 286
Location: United States (CA)
Send PM
Re: Machine R and machine S work at their respective constant rates. How [#permalink]
Expert Reply
Bunuel wrote:
Machine R and machine S work at their respective constant rates. How much time does it take machine R, working alone, to complete a certain job?

(1) The amount of time that it takes machine S, working alone, to complete the job is 3/4 the amount of time that it takes machine R, working alone, to complete the job.
(2) Machine R and machine S, working together, take 12 minutes to complete the job.


NEW question from GMAT® Official Guide 2019


(DS00858)

Solution:

Question Stem Analysis:

We need to determine the amount of time it takes machine R to complete a certain job alone.

Statement One Alone:

From statement one, we see that machine R takes 4/3 the amount of time of machine S to complete the job alone. However, without knowing the amount of time it takes machine S to complete the job alone, we can’t determine the amount of time it takes marchine R to complete the job alone. Statement one alone is not sufficient.

Statement Two Alone:

Knowing that it takes 12 minutes for machine R and machine S, combined, to complete the job is not sufficient to ascertain the amount of time it takes for machine R to complete the job alone. Statement two alone is not sufficient.

Statements One and Two Together:

If we let x be the amount of time (in minutes) it takes machine R to complete the job alone, then its rate is 1/x. We know it takes machine S4/3 the time it takes machine R, so its time is 4x/3 minutes, and its rate is 1/(4x/3). Since it takes them 12 minutes to complete the job when working together, we can create the rate equation:

1/x + 1/(4x/3) = 1/12

Without actually solving the equation, we see that we can determine a value for x. The two statements together are sufficient.

Answer: C
Tutor
Joined: 17 Jul 2019
Posts: 1304
Own Kudos [?]: 2137 [0]
Given Kudos: 66
Location: Canada
GMAT 1: 780 Q51 V45
GMAT 2: 780 Q50 V47
GMAT 3: 770 Q50 V45
Send PM
Re: Machine R and machine S work at their respective constant rates. How [#permalink]
Expert Reply
Video solution from Quant Reasoning:
Subscribe for more: https://www.youtube.com/QuantReasoning? ... irmation=1
User avatar
Non-Human User
Joined: 09 Sep 2013
Posts: 33549
Own Kudos [?]: 837 [0]
Given Kudos: 0
Send PM
Re: Machine R and machine S work at their respective constant rates. How [#permalink]
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.
GMAT Club Bot
Re: Machine R and machine S work at their respective constant rates. How [#permalink]
Moderator:
Math Expert
93696 posts