Machine M and Machine N working alone at their constant rate : GMAT Data Sufficiency (DS)
Check GMAT Club App Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

It is currently 09 Dec 2016, 16:22
GMAT Club Tests

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Machine M and Machine N working alone at their constant rate

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

Hide Tags

Intern
Intern
User avatar
Joined: 24 May 2014
Posts: 13
Location: Brazil
Followers: 0

Kudos [?]: 67 [0], given: 6

Machine M and Machine N working alone at their constant rate [#permalink]

Show Tags

New post 26 Jul 2014, 09:07
15
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  95% (hard)

Question Stats:

43% (02:35) correct 57% (01:38) wrong based on 343 sessions

HideShow timer Statistics

Machine M and Machine N working alone at their constant rates, non stop, produced 6000 and 8000 nails respectively. Did machine M work longer than machine N?

(1) Machine N produces 2000 more nails than machine M in one hour when each machine work at its constant rate

(2) Machine N produces twice as much as machine M in one hour when each machine work at its constant rate
[Reveal] Spoiler: OA
Expert Post
5 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 35932
Followers: 6860

Kudos [?]: 90100 [5] , given: 10413

Re: Machine M and Machine N working alone at their constant rate [#permalink]

Show Tags

New post 26 Jul 2014, 09:37
5
This post received
KUDOS
Expert's post
7
This post was
BOOKMARKED
Machine M and Machine N working alone at their constant rates, non stop, produced 6000 and 8000 nails respectively. Did machine M work longer than machine N?

(1) Machine N produces 2000 more nails than machine M in one hour when each machine work at its constant rate.

If the rate of M is 2,000 nails per hour and the rate of N is 4,000 nails per hour, then to produce 6,000 nails, M needs 3 hours and to produce 8,000 nails N, needs 2 hours. In this case M worked longer than N.

If the rate of M is 6,000 nails per hour and the rate of N is 8,000 nails per hour, then to produce 6,000 nails, M needs 1 hours and to produce 8,000 nails N, needs 1 hour. In this case M did not work longer than N.

Not sufficient.

(2) Machine N produces twice as much as machine M in one hour when each machine work at its constant rate. In the time M needs to produce 6,000 nails, N can produce 12,000 nails, thus it can produce 8,000 nails in less time than M can produce 6,000 nails. Sufficient.

Answer: B.
_________________

New to the Math Forum?
Please read this: All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Current Student
User avatar
Status: Everyone is a leader. Just stop listening to others.
Joined: 22 Mar 2013
Posts: 992
Location: India
GPA: 3.51
WE: Information Technology (Computer Software)
Followers: 163

Kudos [?]: 1427 [0], given: 227

Premium Member Reviews Badge
Re: Machine M and Machine N working alone at their constant rate [#permalink]

Show Tags

New post 05 Sep 2014, 06:22
Machine M and Machine N working alone at their constant rates, non stop, produced 6000 and 8000 nails respectively. Did machine M work longer than machine N?

Let N is number of nails machine N produced.
Let M is number of nails machine M produced.
And x and y are respective time each machine took to produce 6000 and 8000 nails.

(1) Machine N produces 2000 more nails than machine M in one hour when each machine work at its constant rate

Given N= M + 2000
Mx = 6000 ------(1)
Ny = 8000 ==> (M+2000)y=8000 ---------(2)
Solve 1 and 2 to find ratio of x/y.

\((\frac{6000}{x}+2000)y=8000\)
We can not reduce this equation in \(x/y\) form. Thus, (1) insufficient.

(2) Machine N produces twice as much as machine M in one hour when each machine work at its constant rate.
N=2M

Mx = 6000 --------(1)
Ny = 8000 ==> 2My=8000 -------(2)

\(2y\frac{6000}{x}=8000\)
Solve for \(x/y\); we can calculate x:y. Thus, statement (2) is sufficient.
_________________

Piyush K
-----------------------
Our greatest weakness lies in giving up. The most certain way to succeed is to try just one more time. ― Thomas A. Edison
Don't forget to press--> Kudos :)
My Articles: 1. WOULD: when to use? | 2. All GMATPrep RCs (New)
Tip: Before exam a week earlier don't forget to exhaust all gmatprep problems specially for "sentence correction".

Intern
Intern
avatar
Joined: 15 Sep 2013
Posts: 1
Followers: 0

Kudos [?]: 0 [0], given: 4

Re: Machine M and Machine N working alone at their constant rate [#permalink]

Show Tags

New post 07 Sep 2014, 08:33
Hi Bunuel,

Why are we rounding off the number of hours here?
Am i missing something in the question, why arent we considering minutes, for which im getting the first statement as being sufficient.
Thanks
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 35932
Followers: 6860

Kudos [?]: 90100 [0], given: 10413

Re: Machine M and Machine N working alone at their constant rate [#permalink]

Show Tags

New post 07 Sep 2014, 08:43
shishir16 wrote:
Hi Bunuel,

Why are we rounding off the number of hours here?
Am i missing something in the question, why arent we considering minutes, for which im getting the first statement as being sufficient.
Thanks


Cannot follow what you mean...

Where do we round the number of hours? Also, in my solution for (1) there are an example given which gives two different answers to the question, which means that this statement is not sufficient.
_________________

New to the Math Forum?
Please read this: All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Current Student
User avatar
Joined: 06 Mar 2014
Posts: 276
Location: India
GMAT Date: 04-30-2015
Followers: 0

Kudos [?]: 68 [0], given: 84

Reviews Badge
Re: Machine M and Machine N working alone at their constant rate [#permalink]

Show Tags

New post 07 Sep 2015, 03:15
Bunuel wrote:
Machine M and Machine N working alone at their constant rates, non stop, produced 6000 and 8000 nails respectively. Did machine M work longer than machine N?

(1) Machine N produces 2000 more nails than machine M in one hour when each machine work at its constant rate.

If the rate of M is 2,000 nails per hour and the rate of N is 4,000 nails per hour, then to produce 6,000 nails, M needs 3 hours and to produce 8,000 nails N, needs 2 hours. In this case M worked longer than N.

If the rate of M is 6,000 nails per hour and the rate of N is 8,000 nails per hour, then to produce 6,000 nails, M needs 1 hours and to produce 8,000 nails N, needs 1 hour. In this case M did not work longer than N.

Not sufficient.

(2) Machine N produces twice as much as machine M in one hour when each machine work at its constant rate. In the time M needs to produce 6,000 nails, N can produce 12,000 nails, thus it can produce 8,000 nails in less time than M can produce 6,000 nails. Sufficient.

Answer: B.



The highlighted part: If the question is to produce 6000 nails then definitely M needs 1 hour but N with a rate of 8000 nails per hour would need less than an hour right?

Please clarify if possible.
Thank you.
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 35932
Followers: 6860

Kudos [?]: 90100 [0], given: 10413

Re: Machine M and Machine N working alone at their constant rate [#permalink]

Show Tags

New post 07 Sep 2015, 04:06
earnit wrote:
Bunuel wrote:
Machine M and Machine N working alone at their constant rates, non stop, produced 6000 and 8000 nails respectively. Did machine M work longer than machine N?

(1) Machine N produces 2000 more nails than machine M in one hour when each machine work at its constant rate.

If the rate of M is 2,000 nails per hour and the rate of N is 4,000 nails per hour, then to produce 6,000 nails, M needs 3 hours and to produce 8,000 nails N, needs 2 hours. In this case M worked longer than N.

If the rate of M is 6,000 nails per hour and the rate of N is 8,000 nails per hour, then to produce 6,000 nails, M needs 1 hours and to produce 8,000 nails N, needs 1 hour. In this case M did not work longer than N.

Not sufficient.

(2) Machine N produces twice as much as machine M in one hour when each machine work at its constant rate. In the time M needs to produce 6,000 nails, N can produce 12,000 nails, thus it can produce 8,000 nails in less time than M can produce 6,000 nails. Sufficient.

Answer: B.



The highlighted part: If the question is to produce 6000 nails then definitely M needs 1 hour but N with a rate of 8000 nails per hour would need less than an hour right?

Please clarify if possible.
Thank you.


How does N, at the rate of 8,000 nails per hour, need more than an hour to produce 8000 nails? It will need exactly 1 hour.

Again, the question asks: did machine M (which produced 6000 nails) work longer than machine N (which produced 8000 nails)?

If the rate of M is 6,000 nails per hour and the rate of N is 8,000 nails per hour, then to produce 6,000 nails, M needs 1 hours and to produce 8,000 nails N, needs 1 hour. In this case M did not work longer than N.
_________________

New to the Math Forum?
Please read this: All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Current Student
User avatar
Joined: 06 Mar 2014
Posts: 276
Location: India
GMAT Date: 04-30-2015
Followers: 0

Kudos [?]: 68 [0], given: 84

Reviews Badge
Re: Machine M and Machine N working alone at their constant rate [#permalink]

Show Tags

New post 07 Sep 2015, 07:06
Bunuel wrote:
earnit wrote:
Bunuel wrote:
Machine M and Machine N working alone at their constant rates, non stop, produced 6000 and 8000 nails respectively. Did machine M work longer than machine N?

(1) Machine N produces 2000 more nails than machine M in one hour when each machine work at its constant rate.

If the rate of M is 2,000 nails per hour and the rate of N is 4,000 nails per hour, then to produce 6,000 nails, M needs 3 hours and to produce 8,000 nails N, needs 2 hours. In this case M worked longer than N.

If the rate of M is 6,000 nails per hour and the rate of N is 8,000 nails per hour, then to produce 6,000 nails, M needs 1 hours and to produce 8,000 nails N, needs 1 hour. In this case M did not work longer than N.

Not sufficient.

(2) Machine N produces twice as much as machine M in one hour when each machine work at its constant rate. In the time M needs to produce 6,000 nails, N can produce 12,000 nails, thus it can produce 8,000 nails in less time than M can produce 6,000 nails. Sufficient.

Answer: B.



The highlighted part: If the question is to produce 6000 nails then definitely M needs 1 hour but N with a rate of 8000 nails per hour would need less than an hour right?

Please clarify if possible.
Thank you.


How does N, at the rate of 8,000 nails per hour, need more than an hour to produce 8000 nails? It will need exactly 1 hour.

Again, the question asks: did machine M (which produced 6000 nails) work longer than machine N (which produced 8000 nails)?

If the rate of M is 6,000 nails per hour and the rate of N is 8,000 nails per hour, then to produce 6,000 nails, M needs 1 hours and to produce 8,000 nails N, needs 1 hour. In this case M did not work longer than N.



Got it.
Its not the common number that the machines are expected to produce.
That part slipped out when exploring the options.

Key take away: if there is a common number required to produce then even (1) would be sufficient. But not in the above case.
Expert Post
Math Revolution GMAT Instructor
User avatar
Joined: 16 Aug 2015
Posts: 2305
GPA: 3.82
Followers: 160

Kudos [?]: 1318 [0], given: 0

Premium Member CAT Tests
Machine M and Machine N working alone at their constant rate [#permalink]

Show Tags

New post 08 Sep 2015, 06:38
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and equations ensures a solution.


Machine M and Machine N working alone at their constant rates, non stop, produced 6000 and 8000 nails respectively. Did machine M work longer than machine N?

(1) Machine N produces 2000 more nails than machine M in one hour when each machine work at its constant rate

(2) Machine N produces twice as much as machine M in one hour when each machine work at its constant rate

In the original condition, r1*t1=6000, r2*t2=8000 and throw some transformation we have t1=6000/r1, t2=8000/r2 and 6000/r1>8000/r2, 3r2>4r1?, therefore the question is all about comparing r1 and r2.
We have 4 variables (r1,r2,t1,t2), 2 equations (r1*t1=6000, r2*t2=8000) therefore we need 2 more equations and therefore C is likely the answer. Using both 1) & 2) together, r2=r1+2000, r2=2r1 gives us r1=2000, r2=4000 and thus C is the answer. But such trivial conditions are rarely the answer, so we might try it separately again.

Using 1), 2)separately, (from Common mistake type 4(A), in case of 2) substituting r2=2r1 to 3r2>4r1? gives us 3*2r1>4r1?, 6>4. Therefore the answer is yes, and the condition is sufficient. Therefore the answer is B. (when looking at conditions 1), 2) if one is given by value and the other is given by ratio, the one with ratio is usually the answer. That's why we just calculated using con 1) here. )
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 12904
Followers: 562

Kudos [?]: 158 [0], given: 0

Premium Member
Re: Machine M and Machine N working alone at their constant rate [#permalink]

Show Tags

New post 21 Nov 2016, 15:37
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: Machine M and Machine N working alone at their constant rate   [#permalink] 21 Nov 2016, 15:37
    Similar topics Author Replies Last post
Similar
Topics:
7 If machine J, working alone at its constant rate, takes 2 minutes to ajaym28 6 25 Oct 2014, 03:14
61 Experts publish their posts in the topic A newer machine, working alone at its constant rate gmacforjyoab 26 26 Oct 2013, 13:42
69 Experts publish their posts in the topic Machine M, working alone at its constant rate, produces x wi violetsplash 15 24 Sep 2013, 07:29
96 Experts publish their posts in the topic Machines X and Y work at their respective constant rates BANON 19 23 Feb 2012, 08:05
17 Working at their respective constant rates, machine A makes banksy 12 09 Mar 2011, 14:03
Display posts from previous: Sort by

Machine M and Machine N working alone at their constant rate

  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 and phpBB SEO

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®.