It is currently 21 Aug 2017, 02:59

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

X number of men can finish a piece of work in 30 days

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Manager
Manager
avatar
P
Joined: 28 May 2014
Posts: 164

Kudos [?]: 101 [0], given: 63

GMAT ToolKit User Premium Member
X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 09 Feb 2017, 00:09
3
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

77% (02:28) correct 23% (01:48) wrong based on 128 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
[Reveal] Spoiler: OA

Kudos [?]: 101 [0], given: 63

2 KUDOS received
Senior Manager
Senior Manager
avatar
B
Joined: 13 Oct 2016
Posts: 367

Kudos [?]: 368 [2] , given: 40

GPA: 3.98
Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 09 Feb 2017, 00:40
2
This post received
KUDOS
2
This post was
BOOKMARKED
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

Kudos [?]: 368 [2] , given: 40

3 KUDOS received
Manager
Manager
avatar
P
Joined: 17 May 2015
Posts: 191

Kudos [?]: 168 [3] , given: 70

Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 09 Feb 2017, 03:06
3
This post received
KUDOS
3
This post was
BOOKMARKED
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.

Kudos [?]: 168 [3] , given: 70

Director
Director
avatar
S
Joined: 07 Dec 2014
Posts: 775

Kudos [?]: 204 [0], given: 8

Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 09 Feb 2017, 11:23
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

Kudos [?]: 204 [0], given: 8

Expert Post
2 KUDOS received
Veritas Prep GMAT Instructor
User avatar
G
Joined: 16 Oct 2010
Posts: 7567

Kudos [?]: 16439 [2] , given: 229

Location: Pune, India
Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 10 Feb 2017, 00:18
2
This post received
KUDOS
Expert's post
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
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

Kudos [?]: 16439 [2] , given: 229

Intern
Intern
avatar
B
Joined: 11 Jan 2013
Posts: 8

Kudos [?]: 5 [0], given: 6

Concentration: Healthcare
Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 14 Feb 2017, 20:25
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"?

Kudos [?]: 5 [0], given: 6

Expert Post
Veritas Prep GMAT Instructor
User avatar
G
Joined: 16 Oct 2010
Posts: 7567

Kudos [?]: 16439 [0], given: 229

Location: Pune, India
Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 15 Feb 2017, 01:37
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 ... of-ratios/

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
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

Kudos [?]: 16439 [0], given: 229

Expert Post
Target Test Prep Representative
User avatar
S
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 1375

Kudos [?]: 722 [0], given: 2

Location: United States (CA)
Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 15 Feb 2017, 10:51
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 Woodbury-Stewart
Founder and CEO

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Kudos [?]: 722 [0], given: 2

Intern
Intern
avatar
B
Joined: 11 Jan 2013
Posts: 8

Kudos [?]: 5 [0], given: 6

Concentration: Healthcare
X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 15 Feb 2017, 20:37
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.

Last edited by cara0910 on 20 Feb 2017, 09:42, edited 1 time in total.

Kudos [?]: 5 [0], given: 6

BSchool Forum Moderator
User avatar
S
Joined: 28 Nov 2014
Posts: 927

Kudos [?]: 187 [0], given: 79

Concentration: Strategy
Schools: Fisher '19 (M)
GPA: 3.71
Reviews Badge
Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 15 Feb 2017, 23:07
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

Kudos [?]: 187 [0], given: 79

Expert Post
1 KUDOS received
EMPOWERgmat Instructor
User avatar
G
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 9584

Kudos [?]: 3189 [1] , given: 170

Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: 340 Q170 V170
Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 17 Feb 2017, 12:39
1
This post received
KUDOS
Expert's post
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 worker-days 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 worker-days 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:
[Reveal] Spoiler:
C


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

Co-Founder & 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!***********************

Kudos [?]: 3189 [1] , given: 170

Manager
Manager
avatar
P
Joined: 17 May 2015
Posts: 191

Kudos [?]: 168 [0], given: 70

Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 17 Feb 2017, 23:37
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 worker-days 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 worker-days 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:
[Reveal] Spoiler:
C


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.

Kudos [?]: 168 [0], given: 70

Expert Post
EMPOWERgmat Instructor
User avatar
G
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 9584

Kudos [?]: 3189 [0], given: 170

Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: 340 Q170 V170
Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 18 Feb 2017, 14:12
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

Co-Founder & 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!***********************

Kudos [?]: 3189 [0], given: 170

Intern
Intern
avatar
B
Joined: 12 Feb 2016
Posts: 3

Kudos [?]: 0 [0], given: 1

Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 16 Apr 2017, 13:23
(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

Kudos [?]: 0 [0], given: 1

Manager
Manager
avatar
B
Joined: 09 Mar 2017
Posts: 77

Kudos [?]: 23 [0], given: 1

Location: Indonesia
Concentration: General Management, Finance
Schools: Erasmus '18 (A)
GMAT 1: 670 Q47 V36
GPA: 2.8
Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 16 Apr 2017, 23:23
1/20-1/30=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

Kudos [?]: 23 [0], given: 1

Intern
Intern
avatar
B
Joined: 16 Nov 2016
Posts: 32

Kudos [?]: 5 [0], given: 2

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

New post 06 Jun 2017, 11:55
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 :oops:

Kudos [?]: 5 [0], given: 2

Manager
Manager
avatar
P
Joined: 17 May 2015
Posts: 191

Kudos [?]: 168 [0], given: 70

Re: X number of men can finish a piece of work in 30 days [#permalink]

Show Tags

New post 06 Jun 2017, 23:36
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 / 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 :oops:

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.

Kudos [?]: 168 [0], given: 70

Re: X number of men can finish a piece of work in 30 days   [#permalink] 06 Jun 2017, 23:36
    Similar topics Author Replies Last post
Similar
Topics:
5 Experts publish their posts in the topic 2 men and 3 boys can do a piece of work in 10 days while 3 men and 2 Chemerical71 5 16 Apr 2017, 23:58
14 Experts publish their posts in the topic Twenty workers can finish a piece of work in 30 days saswata4s 7 17 Mar 2017, 02:22
10 Experts publish their posts in the topic 2 men and 3 women can finish a piece of work in 10 days. while 4 men c rohit8865 6 09 Feb 2017, 03:56
15 Experts publish their posts in the topic If 6 men can do a piece of work in 30 days of 9 hours each, smartyman 8 25 Sep 2016, 13:06
16 Experts publish their posts in the topic Matt and Peter can do together a piece of work in 20 days prasannar 15 04 May 2016, 08:02
Display posts from previous: Sort by

X number of men can finish a piece of work in 30 days

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.