February 17, 2019 February 17, 2019 07:00 AM PST 09:00 AM PST Attend this Free Algebra Webinar and learn how to master Inequalities and Absolute Value problems on GMAT. February 18, 2019 February 18, 2019 10:00 PM PST 11:00 PM PST We don’t care what your relationship status this year  we love you just the way you are. AND we want you to crush the GMAT!
Author 
Message 
TAGS:

Hide Tags

Current Student
Joined: 27 May 2014
Posts: 524

X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
08 Feb 2017, 23:09
Question Stats:
80% (01:53) correct 20% (02:20) wrong based on 204 sessions
HideShow timer Statistics
X number of men can finish a piece of work in 30 days. If there were 6 men more, the work could be finished in 10 days less. What is the original number of men? (A) 10 (B) 11 (C) 12 (D) 14 (E) 15
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
440 to 730: If I Can, You Can Too




Manager
Joined: 17 May 2015
Posts: 249

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
09 Feb 2017, 02:06
saswata4s wrote: X number of men can finish a piece of work in 30 days. If there were 6 men more, the work could be finished in 10 days less. What is the original number of men? (A) 10 (B) 11 (C) 12 (D) 14 (E) 15 Hi, X number of men can finish a piece of work in 30 days. ==> Total work = 30X Men days.  (1) If there were 6 men more, the work could be finished in 10 days less. ==> Total work = (X+6)*20 days  (2) By (1) and (2) we have: 30X = (X+6)*20 => 10X = 120 => X = 12 men. Thanks.




Senior Manager
Joined: 13 Oct 2016
Posts: 367
GPA: 3.98

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
08 Feb 2017, 23:40
saswata4s wrote: X number of men can finish a piece of work in 30 days. If there were 6 men more, the work could be finished in 10 days less. What is the original number of men? (A) 10 (B) 11 (C) 12 (D) 14 (E) 15 y#of days one man will finish the work. \(\frac{x}{y} = \frac{1}{30}\) \(y = 30x\) \(\frac{x + 6}{y} = \frac{1}{20}\) \(\frac{x + 6}{30x} = \frac{1}{20}\) \(20x + 120 = 30x\) \(x = 12\) Answer C



VP
Joined: 07 Dec 2014
Posts: 1157

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
09 Feb 2017, 10:23
saswata4s wrote: X number of men can finish a piece of work in 30 days. If there were 6 men more, the work could be finished in 10 days less. What is the original number of men? (A) 10 (B) 11 (C) 12 (D) 14 (E) 15 rate of 1 man per day=1/30x (x+6)*1/30x*20=1 x=12 C



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8882
Location: Pune, India

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
09 Feb 2017, 23:18
saswata4s wrote: X number of men can finish a piece of work in 30 days. If there were 6 men more, the work could be finished in 10 days less. What is the original number of men? (A) 10 (B) 11 (C) 12 (D) 14 (E) 15 Using Ratios: X men do 1/30th of the work per day. X+6 men will do 1/20th of the work per day. So ratio of men in the two cases is (1/30)/(1/20) = 2/3 On the ratio scale, the additional 1 is actually 6 so the multiplier is 6. Hence original number of men = 2*6 = 12 Answer (C)
_________________
Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >



Current Student
Joined: 11 Jan 2013
Posts: 29

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
14 Feb 2017, 19:25
VeritasPrepKarishma wrote: saswata4s wrote: X number of men can finish a piece of work in 30 days. If there were 6 men more, the work could be finished in 10 days less. What is the original number of men? (A) 10 (B) 11 (C) 12 (D) 14 (E) 15 Using Ratios: X men do 1/30th of the work per day. X+6 men will do 1/20th of the work per day. So ratio of men in the two cases is (1/30)/(1/20) = 2/3 On the ratio scale, the additional 1 is actually 6 so the multiplier is 6. Hence original number of men = 2*6 = 12 Answer (C) Hi Karishma, can you break this down a bit more? I understand the ratio of rates is 2/3, but what did you mean "on the ratio scale, the additional 1 is actually 6"?



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8882
Location: Pune, India

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
15 Feb 2017, 00:37
cara0910 wrote: VeritasPrepKarishma wrote: saswata4s wrote: X number of men can finish a piece of work in 30 days. If there were 6 men more, the work could be finished in 10 days less. What is the original number of men? (A) 10 (B) 11 (C) 12 (D) 14 (E) 15 Using Ratios: X men do 1/30th of the work per day. X+6 men will do 1/20th of the work per day. So ratio of men in the two cases is (1/30)/(1/20) = 2/3 On the ratio scale, the additional 1 is actually 6 so the multiplier is 6. Hence original number of men = 2*6 = 12 Answer (C) Hi Karishma, can you break this down a bit more? I understand the ratio of rates is 2/3, but what did you mean "on the ratio scale, the additional 1 is actually 6"? Sure. Take a look at this post: https://www.veritasprep.com/blog/2011/0 ... ofratios/You have the ratio scale, a multiplier and the actual values. e.g. On the ratio scale, A:B = 2:3. If the multiplier is 6, actual values are A = 6*2 = 12 and B = 6*3 = 18
_________________
Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >



Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 4920
Location: United States (CA)

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
15 Feb 2017, 09:51
saswata4s wrote: X number of men can finish a piece of work in 30 days. If there were 6 men more, the work could be finished in 10 days less. What is the original number of men? (A) 10 (B) 11 (C) 12 (D) 14 (E) 15 We are given that X men can complete a job in 30 days. Since rate = work/time, the rate of the X men is 1/30. We are also given that if 6 more men were added, the work could be finished in 10 fewer days (i.e., the work could be finished in 20 days). Thus the rate of X + 6 men would be 1/20. To determine X, we create the following proportion: X/(1/30) = (X + 6)/(1/20) 30X = 20(X + 6) 30X = 20X + 120 10X = 120 X = 12 Answer: C
_________________
Scott WoodburyStewart
Founder and CEO
GMAT Quant SelfStudy Course
500+ lessons 3000+ practice problems 800+ HD solutions



Current Student
Joined: 11 Jan 2013
Posts: 29

X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
Updated on: 20 Feb 2017, 08:42
VeritasPrepKarishma wrote: You have the ratio scale, a multiplier and the actual values.
e.g. On the ratio scale, A:B = 2:3. If the multiplier is 6, actual values are A = 6*2 = 12 and B = 6*3 = 18
Thanks! This was a good read.
Originally posted by okfan01 on 15 Feb 2017, 19:37.
Last edited by okfan01 on 20 Feb 2017, 08:42, edited 1 time in total.



Current Student
Joined: 28 Nov 2014
Posts: 847
Concentration: Strategy
GPA: 3.71

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
15 Feb 2017, 22:07
You can straight away apply a formula here.
(M1D1H1)/W1 = (M2D2H2)/W2
Where M1, M2 = Number of men/women H1,H2 = Number of hours worked D1,D2 = Number of days worked and W1,W2 = Work done
Here, the case will be
(X)30 = (X+6)(20) X=12



EMPOWERgmat Instructor
Status: GMAT Assassin/CoFounder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 13546
Location: United States (CA)

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
17 Feb 2017, 11:39
Hi saswata4s, This question can be solved by TESTing THE ANSWERS. Since the numbers involved in the prompt are all EVEN numbers (and there are no fractions or decimals involved), then it's likely that the correct answer will also be an even number. This is essentially a rate question, so it will help to think in those terms... Let's TEST Answer A: 10 workers IF... 10 workers require 30 days to complete a job, then that is (10)(30) = 300 workerdays of effort to complete the task. With 10+6 = 16 workers, we would need 300/16 = 18 3/4 days to complete the task. This difference does NOT match what we were told (it's supposed to be 20 days). Eliminate Answer A. Let's TEST Answer C: 12 workers IF... 12 workers require 30 days to complete a job, then that is (12)(30) = 360 workerdays of effort to complete the task. With 12+6 = 18 workers, we would need 360/18 = 20 days to complete the task. This is an exact match for what we were told, so this MUST be the answer. Final Answer: GMAT assassins aren't born, they're made, Rich
_________________
760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com
Rich Cohen
CoFounder & GMAT Assassin
Special Offer: Save $75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/
*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****



Manager
Joined: 17 May 2015
Posts: 249

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
17 Feb 2017, 22:37
EMPOWERgmatRichC wrote: Hi saswata4s, This question can be solved by TESTing THE ANSWERS. Since the numbers involved in the prompt are all EVEN numbers (and there are no fractions or decimals involved), then it's likely that the correct answer will also be an even number. This is essentially a rate question, so it will help to think in those terms... Let's TEST Answer A: 10 workers IF... 10 workers require 30 days to complete a job, then that is (10)(30) = 300 workerdays of effort to complete the task. With 10+6 = 16 workers, we would need 300/16 = 18 3/4 days to complete the task. This difference does NOT match what we were told (it's supposed to be 20 days). Eliminate Answer A. Let's TEST Answer C: 12 workers IF... 12 workers require 30 days to complete a job, then that is (12)(30) = 360 workerdays of effort to complete the task. With 12+6 = 18 workers, we would need 360/18 = 20 days to complete the task. This is an exact match for what we were told, so this MUST be the answer. Final Answer: GMAT assassins aren't born, they're made, Rich Hi EMPOWERgmatRichC, Quote: This question can be solved by TESTing THE ANSWERS. I think if options are in increasing/decreasing order then we should start checking with middle option, i.e. (C). It helps us to eliminate two other options in one shot. Thanks.



EMPOWERgmat Instructor
Status: GMAT Assassin/CoFounder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 13546
Location: United States (CA)

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
18 Feb 2017, 13:12
Hi ganand, When TESTing THE ANSWERS, it helps to consider all of the information that you're given (including the 'design' of the answer choices and the specific question that is asked) when choosing which answer to TEST first. To that end, starting with Answer C is often not the best option (as 80% of the time you'll be forced to check a second option to get to the correct answer). GMAT assassins aren't born, they're made, Rich
_________________
760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com
Rich Cohen
CoFounder & GMAT Assassin
Special Offer: Save $75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/
*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****



Intern
Joined: 12 Feb 2016
Posts: 3

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
16 Apr 2017, 12:23
(1): X*(1/m) = 1/30 (X men do 1/30 work a day) (2): (X+6)*(1/m) = 1/20 ((X + 6) men do 1/20 work a day) (1)/(2) = X/(X+6) = 2/3 > 3X = 2X + 12 > X = 12



Current Student
Joined: 09 Mar 2017
Posts: 91
Location: Netherlands
Concentration: General Management, Finance

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
16 Apr 2017, 22:23
1/201/30=1/60 So 6 men will make 1/60 more job per day which makes 1 men do 1/360 job per day 360/30= 12 men as original number



Intern
Joined: 16 Nov 2016
Posts: 30
Location: India
Concentration: Finance, International Business
GPA: 3.78
WE: Accounting (Accounting)

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
06 Jun 2017, 10:55
What if you consider the total units to be 600 and so with X men 30 days  600 units then in 1 day he makes 20 units. therefore for X men it is 20X units / day X+6 men  20 days  600 units then in 1 day he makes 30 units therefore for X+6 men it is 30 (X+6)=30X+180. Then equate the two to get the value of X. But i am unable to get the answer. Can someone please let me know why is my method wrong and where am i getting deviated. Thank you



Manager
Joined: 17 May 2015
Posts: 249

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
06 Jun 2017, 22:36
muthappashivani wrote: What if you consider the total units to be 600 and so with X men 30 days  600 units then in 1 day he makes 20 units. therefore for X men it is 20X units / dayX+6 men  20 days  600 units then in 1 day he makes 30 units therefore for X+6 men it is 30 (X+6)=30X+180. Then equate the two to get the value of X. But i am unable to get the answer. Can someone please let me know why is my method wrong and where am i getting deviated. Thank you Hi muthappashivani, Please refer the highlighted part. x men 30 days  600 units => x men in 1 day  20 units => 1 men in 1 day  20/x units.  (1) x+6 men 20 days  600 units => x+6 men in 1 day  30 units => 1 men in 1 day  30/(x+6) units. (2) Equate (1) and (2), we have: \(\frac{20}{x} = \frac{30}{x+6} \Rightarrow 30x = 20x + 120 \Rightarrow x = 12\) Hope it helps. Thanks.



NonHuman User
Joined: 09 Sep 2013
Posts: 9839

Re: X number of men can finish a piece of work in 30 days
[#permalink]
Show Tags
14 Oct 2018, 07:06
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 Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: X number of men can finish a piece of work in 30 days
[#permalink]
14 Oct 2018, 07:06






