It is currently 19 Jan 2018, 21:26

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

Six machines, each working at the same constant rate

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

Hide Tags

Intern
Intern
avatar
B
Joined: 05 Sep 2016
Posts: 9

Kudos [?]: 1 [0], given: 148

Re: Six machines, each working at the same constant rate [#permalink]

Show Tags

New post 04 Dec 2016, 01:34
if 6 machines do the job in 12 hours, then the ratio is 6:12.
if we want to do the same job in 8 hours, then 12 need to be multiplied by 2/3, 12 * 2/3 = 8.
Thus, since work and time are reciprocal, 6 machines have to be multiplied by 3/2, then 6 * 3/2 = 9.
The answer is 9 - 6 = 3 additional machines.

Kudos [?]: 1 [0], given: 148

Intern
Intern
avatar
S
Joined: 13 Dec 2016
Posts: 45

Kudos [?]: 10 [0], given: 571

Re: Six machines, each working at the same constant rate [#permalink]

Show Tags

New post 20 Jan 2017, 01:06
A simple way to solve this problem is to form an equation based on inverse proportion :
If 6 machines take 12 days to complete the job, logic says that more machines will be needed to do the same job in less no. of days (here 8 days).
Let x be the additional machines needed to complete the job in 8 days.
Hence, our equation will be:
6/ (6+x) = 8/12
Solve it for x to get 3 as the answer

Kudos [?]: 10 [0], given: 571

Intern
Intern
avatar
B
Joined: 23 Sep 2016
Posts: 38

Kudos [?]: 7 [0], given: 81

Location: United States (CT)
Concentration: Finance, International Business
GPA: 3.81
WE: Analyst (Venture Capital)
GMAT ToolKit User Reviews Badge
Re: Six machines, each working at the same constant rate [#permalink]

Show Tags

New post 20 Feb 2017, 16:35
Six machines to complete a job in 12 days means that every day each machine completes 1/72 of the job. So to complete a job in 8 days it would take 9 machines since 9 machines complete 9/72 of the job a day. Multiplied by 8 it will take those 9 machines 8 days to complete 72/72 percent of the job which is 100%.

Kudos [?]: 7 [0], given: 81

Manager
Manager
avatar
S
Joined: 03 Jan 2017
Posts: 194

Kudos [?]: 11 [0], given: 4

Re: Six machines, each working at the same constant rate [#permalink]

Show Tags

New post 28 Mar 2017, 10:00
speed time work
6 machines 6x 12 1
? ? 8 1

As we know that machiens do the same work, we can say x=1, then they do 72, 72/8=9, 9-6=3 answer is 3

Kudos [?]: 11 [0], given: 4

Manager
Manager
User avatar
G
Joined: 27 Dec 2016
Posts: 232

Kudos [?]: 55 [0], given: 249

Concentration: Social Entrepreneurship, Nonprofit
GPA: 3.65
WE: Sales (Consumer Products)
Premium Member Reviews Badge
Six machines, each working at the same constant rate [#permalink]

Show Tags

New post 22 Apr 2017, 14:47
srkaleem wrote:
Six machines, each working at the same constant rate, together can complete a job in 12 days. How many additional machines, each working at the same constant rate, will be needed to complete the job in 8 days?

A. 2
B. 3
C. 4
D. 6
E. 8


Solution :

1. 1/12 = 6 X \(\frac{1}{X}\), thus we get X = 72.

2. \(\frac{6}{X}\) + ( y X \(\frac{1}{X}\) ) = 1/8, plugging X value = 72; thus we get y = 6

3. Difference between 2 value is the answer, thus = 3.
_________________

There's an app for that - Steve Jobs.

Kudos [?]: 55 [0], given: 249

Manager
Manager
avatar
B
Joined: 30 Apr 2013
Posts: 95

Kudos [?]: [0], given: 9

CAT Tests
Re: Six machines, each working at the same constant rate [#permalink]

Show Tags

New post 18 Dec 2017, 02:07
Could we solve this problem by assuming numbers for work?

Kudos [?]: [0], given: 9

Re: Six machines, each working at the same constant rate   [#permalink] 18 Dec 2017, 02:07

Go to page   Previous    1   2   [ 26 posts ] 

Display posts from previous: Sort by

Six machines, each working at the same 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 | 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®.