GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 14 Nov 2018, 22:24

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 in November
PrevNext
SuMoTuWeThFrSa
28293031123
45678910
11121314151617
18192021222324
2526272829301
Open Detailed Calendar
  • $450 Tuition Credit & Official CAT Packs FREE

     November 15, 2018

     November 15, 2018

     10:00 PM MST

     11:00 PM MST

    EMPOWERgmat is giving away the complete Official GMAT Exam Pack collection worth $100 with the 3 Month Pack ($299)
  • Free GMAT Strategy Webinar

     November 17, 2018

     November 17, 2018

     07:00 AM PST

     09:00 AM PST

    Nov. 17, 7 AM PST. Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.

A factory has three types of machines, each of which works a

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

Hide Tags

Manager
Manager
avatar
Joined: 09 Feb 2013
Posts: 118
A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post Updated on: 11 Jun 2013, 05:09
6
40
00:00
A
B
C
D
E

Difficulty:

  65% (hard)

Question Stats:

65% (02:01) correct 35% (02:21) wrong based on 498 sessions

HideShow timer Statistics

A factory has three types of machines, each of which works at its own constant rate. If 7 Machine As and 11 Machine Bs can produce 250 widgets per hour, and if 8 Machine As and 22 Machine Cs can produce 600 widgets per hour, how many widgets could one machine A, one Machine B, and one Machine C produce in one 8-hour day?

A. 400
B. 475
C. 550
D. 625
E. 700

_________________

Kudos will encourage many others, like me.
Good Questions also deserve few KUDOS.


Originally posted by emmak on 11 Jun 2013, 02:05.
Last edited by Bunuel on 11 Jun 2013, 05:09, edited 1 time in total.
Edited the question.
Most Helpful Expert Reply
EMPOWERgmat Instructor
User avatar
V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 12857
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 05 Jun 2015, 10:46
11
4
Hi All,

When dealing with complex-"looking" prompts, it's important to remember that they were DESIGNED to be solved, so sometimes you have to 'play around' with what you're given to get to the correct answer.

From this prompt, we can create two equations:

7A + 11B = 250/hour
8A + 22C = 600/hour

We're asked for (A+B+C)/hour over the course of 8 hours.

With the given equations, we have 3 variables but only 2 equations, so this is NOT a typical "system" question. The answers ARE numbers though, so there must be a way to get to A+B+C from the two equations that we have....

Notice how we have 11B in one equation and 22C an another? It's INTERESTING that they're both multiples of 11.....Maybe that's a 'clue' as to how we can proceed....

If we "double" the entire first equation, we get...

14A + 22B = 500/hour

Now I can add this equation to the second equation:

14A + 22B = 500/hour
8A + 22C = 600/hour

22A + 22B + 22C = 1100/hour

Dividing everything by 22, we get....

A+B+C = 50/hour

Over the course of an 8-hour day, that gives us...50(8) = 400 widgets.

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

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!*****

Most Helpful Community Reply
VP
VP
User avatar
Status: Far, far away!
Joined: 02 Sep 2012
Posts: 1073
Location: Italy
Concentration: Finance, Entrepreneurship
GPA: 3.8
GMAT ToolKit User
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 11 Jun 2013, 02:10
11
6
\(rate*time=work\)

\((7A+11B)*1h=250\)

\((8A+22C)*1h=600\) or \(4A+11C=300\). Sum those equations:

\(7A+11B+4A+11C=550\) or \(11A+11B+11C=550\)

\(A+B+C=50\) every hour, in 8 hours \(50*8=400\)
_________________

It is beyond a doubt that all our knowledge that begins with experience.

Kant , Critique of Pure Reason

Tips and tricks: Inequalities , Mixture | Review: MGMAT workshop
Strategy: SmartGMAT v1.0 | Questions: Verbal challenge SC I-II- CR New SC set out !! , My Quant

Rules for Posting in the Verbal Forum - Rules for Posting in the Quant Forum[/size][/color][/b]

General Discussion
Manager
Manager
avatar
Joined: 25 Oct 2013
Posts: 153
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 20 Jan 2014, 02:48
2
Let Machine A produce A widgets per hour. B produce B widgets per hour and C produce C widgets per hour.
7A+11B=250 ---(1)
8A+22C=600 ---(2)

(1)+(2)
15A+11B+22C=850 split up
11A+11B+11C + 4A+11C = 850---(3)

From (2) 4A+11C=300
Hence (3) becomes
11(A+B+C) = 550
A+B+C = 50. So working together 1 machine of each type produce 50 widgets an hour. in 8 hours they produce 8*50 = 400 widgets.
_________________

Click on Kudos if you liked the post!

Practice makes Perfect.

Senior Manager
Senior Manager
User avatar
Status: Verbal Forum Moderator
Joined: 17 Apr 2013
Posts: 488
Location: India
GMAT 1: 710 Q50 V36
GMAT 2: 750 Q51 V41
GMAT 3: 790 Q51 V49
GPA: 3.3
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 02 Mar 2014, 04:52
gmatprav wrote:
Let Machine A produce A widgets per hour. B produce B widgets per hour and C produce C widgets per hour.
7A+11B=250 ---(1)
8A+22C=600 ---(2)

(1)+(2)
15A+11B+22C=850 split up
11A+11B+11C + 4A+11C = 850---(3)

From (2) 4A+11C=300
Hence (3) becomes
11(A+B+C) = 550
A+B+C = 50. So working together 1 machine of each type produce 50 widgets an hour. in 8 hours they produce 8*50 = 400 widgets.



It as an algebraic manipulation.
_________________

Like my post Send me a Kudos :) It is a Good manner.
My Debrief: http://gmatclub.com/forum/how-to-score-750-and-750-i-moved-from-710-to-189016.html

SVP
SVP
User avatar
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1827
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 02 Mar 2014, 20:11
2
Let Machine A produce A widgets per hour. B produce B widgets per hour and C produce C widgets per hour.
7A+11B=250 ---(1)
8A+22C=600 ---(2)

Dividing (2) by 2
4A+11C=300.....(3)

Adding (1) & (3)

11A+11B+11C = 550
A+B+C=50 per hour

So for eight hrs = 50*8 = 400 = Answer = A
_________________

Kindly press "+1 Kudos" to appreciate :)

Intern
Intern
avatar
B
Joined: 12 Oct 2014
Posts: 3
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 27 Jun 2015, 11:36
1
The only number divisible by 8 is 400. So choice A
Retired Moderator
User avatar
S
Joined: 18 Sep 2014
Posts: 1128
Location: India
GMAT ToolKit User Premium Member Reviews Badge
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 25 Mar 2016, 08:10
waterstyler wrote:
The only number divisible by 8 is 400. So choice A


I'm bit skeptical of the validity of this approach? Can we apply all this kind of problems?
can someone dive deep into this matter?
EMPOWERgmat Instructor
User avatar
V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 12857
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 25 Mar 2016, 10:43
2
Nevernevergiveup wrote:
waterstyler wrote:
The only number divisible by 8 is 400. So choice A


I'm bit skeptical of the validity of this approach? Can we apply all this kind of problems?
can someone dive deep into this matter?


Hi Nevernevergiveup,

You are correct to be cynical about this 'short-cut.' To start, the prompt did NOT state that each machine produces an integer number of widgets per hour, so the conclusion that an 8-hour shift will produce a 'multiple of 8' widgets is questionable. Second (and assuming that all of the hourly rates were integers), if this question had appeared on the Official GMAT, the writers would have anticipated that type of thinking and would have made at least two of the answers divisible by 8. Even if that thinking was correct, it would likely allow the Test Taker to eliminate a few answers, but still be left with an educated guess.

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!*****

Manager
Manager
avatar
B
Joined: 03 May 2014
Posts: 161
Location: India
WE: Sales (Mutual Funds and Brokerage)
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 27 Mar 2016, 09:02
7A+11B=250-eq 1
8A+22C=600-eq 2
Multiply eq one by 2 we get
14A+22B=500
Add above eq to eq 2
14A+22B=500
8A+22C=600
__________
22A+22B+22C=1100
Divide by 22
A+B+C=50 widgets are produced in one Hr.
In 8 hrs no of widgets produced =50x8=400

Posted from my mobile device
Board of Directors
User avatar
P
Joined: 17 Jul 2014
Posts: 2645
Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30
GPA: 3.92
WE: General Management (Transportation)
GMAT ToolKit User Premium Member Reviews Badge
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 10 Oct 2016, 06:34
emmak wrote:
A factory has three types of machines, each of which works at its own constant rate. If 7 Machine As and 11 Machine Bs can produce 250 widgets per hour, and if 8 Machine As and 22 Machine Cs can produce 600 widgets per hour, how many widgets could one machine A, one Machine B, and one Machine C produce in one 8-hour day?

A. 400
B. 475
C. 550
D. 625
E. 700


a question that might seem a nightmare..but very easy to solve, if you know how to approach it...
(1) 1/7A + 1/11B = 250 -> multiply by 2 -> (3) 1/14A + 1/22B = 500
(2) 1/8A + 1/22C = 600

add 2 and 3

1/22A + 1/22B + 1/22C = 1100
divide by 22 => 50
since we need to know how much they do in 8 hours, multiply by 8.

result is 400.

A
Manager
Manager
User avatar
S
Joined: 23 Jan 2016
Posts: 194
Location: India
GPA: 3.2
GMAT ToolKit User Premium Member
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 13 Nov 2016, 01:40
mvictor wrote:
emmak wrote:
A factory has three types of machines, each of which works at its own constant rate. If 7 Machine As and 11 Machine Bs can produce 250 widgets per hour, and if 8 Machine As and 22 Machine Cs can produce 600 widgets per hour, how many widgets could one machine A, one Machine B, and one Machine C produce in one 8-hour day?

A. 400
B. 475
C. 550
D. 625
E. 700


a question that might seem a nightmare..but very easy to solve, if you know how to approach it...
(1) 1/7A + 1/11B = 250 -> multiply by 2 -> (3) 1/14A + 1/22B = 500
(2) 1/8A + 1/22C = 600

add 2 and 3

1/22A + 1/22B + 1/22C = 1100
divide by 22 => 50
since we need to know how much they do in 8 hours, multiply by 8.

result is 400.

A


I really need help here. Lets say rate of one machine A is 1/A, then rate of 7 machine As should be 7/A right?? Can you please elaborate 1/7A which you have taken?
Intern
Intern
avatar
B
Joined: 19 Jan 2016
Posts: 37
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 03 Jun 2017, 02:33
do we have more problems such as this to practice ?? I straight away went for calculating the individual rates and screwed myself
EMPOWERgmat Instructor
User avatar
V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 12857
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 03 Jun 2017, 11:26
Hi anuj11,

Work Formula questions are relatively rare on the Official GMAT - you'll likely see just 1 and it will likely involve 2 entities (re: machines, people, etc.) working on a task. In this prompt, we have 3 entities, which is even rarer. As such, spending a lot of time practicing for this one type of rare prompt probably isn't a good use of your time right now. Make sure that you're nailing all of the BIG categories first before you spend too much energy 'nit-picking' over the rarer question types.

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!*****

Target Test Prep Representative
User avatar
P
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 4170
Location: United States (CA)
Re: A factory has three types of machines, each of which works a  [#permalink]

Show Tags

New post 25 Oct 2018, 08:30
emmak wrote:
A factory has three types of machines, each of which works at its own constant rate. If 7 Machine As and 11 Machine Bs can produce 250 widgets per hour, and if 8 Machine As and 22 Machine Cs can produce 600 widgets per hour, how many widgets could one machine A, one Machine B, and one Machine C produce in one 8-hour day?

A. 400
B. 475
C. 550
D. 625
E. 700


Letting a, b, and c be the hourly output of Machines a, b, and c, respectively, we can create the equations:

7a + 11b = 250

And

8a + 22c = 600

Multiplying the first equation by 2, we have:

14a + 22b = 500

Adding the two equations together we have:

22a + 22b + 22c = 1100

a + b + c = 50

So in 8 hours the 3 machines can produce 400 widgets.

Answer: A
_________________

Scott Woodbury-Stewart
Founder and CEO

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

GMAT Club Bot
Re: A factory has three types of machines, each of which works a &nbs [#permalink] 25 Oct 2018, 08:30
Display posts from previous: Sort by

A factory has three types of machines, each of which works a

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


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| 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®.