Six computers, each working at the same constant rate, together can : GMAT Problem Solving (PS)
Check GMAT Club App Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

It is currently 07 Dec 2016, 14:59
GMAT Club Tests

Chicago-Booth

is Calling R1 Admits |  Join Chat Room2 for Live Updates


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

Six computers, each working at the same constant rate, together can

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

Hide Tags

Senior Manager
Senior Manager
avatar
Joined: 11 May 2010
Posts: 288
Location: United Kingdom
Concentration: Entrepreneurship, Technology
GMAT Date: 10-22-2011
GPA: 3
WE: Information Technology (Internet and New Media)
Followers: 4

Kudos [?]: 60 [0], given: 12

Six computers, each working at the same constant rate, together can [#permalink]

Show Tags

New post 13 Mar 2011, 09:10
5
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

74% (01:59) correct 26% (01:24) wrong based on 164 sessions

HideShow timer Statistics

Six computers, each working at the same constant rate, together can process a certain amount of data in 15 days. How many additional computers, each working at the same constant rate, will be needed to process the same amount of data in 10 days?

(A) 3
(B) 5
(C) 6
(D) 9
(E) 12
[Reveal] Spoiler: OA

Last edited by Bunuel on 20 May 2016, 23:16, edited 1 time in total.
Renamed the topic and edited the question.
Senior Manager
Senior Manager
avatar
Joined: 11 May 2010
Posts: 288
Location: United Kingdom
Concentration: Entrepreneurship, Technology
GMAT Date: 10-22-2011
GPA: 3
WE: Information Technology (Internet and New Media)
Followers: 4

Kudos [?]: 60 [0], given: 12

Re: Six computers, each working at the same constant rate, together can [#permalink]

Show Tags

New post 13 Mar 2011, 09:11
4. A
Explanation: If six computers require 15 days to process the data, that’s
a total of 90 computer-days –the product of 6 and 15. If you change the number
of computers or the number of days, 90 will have to remain the product, whether
that means 90 days of one computer or one day with 90 computers.
In 10 days, the number of computers is:
10c = 90
c = 9
9 computers is 3 more than the 6 that it took to do the job in 15 days, so
the correct choice is (A).


...WHAT I DON'T GET, is this business about "90 computer days"... is there another way to solve it? I wouldn't have known at all to solve it the way they solved it
Expert Post
2 KUDOS received
Veritas Prep GMAT Instructor
User avatar
Joined: 16 Oct 2010
Posts: 7072
Location: Pune, India
Followers: 2086

Kudos [?]: 13291 [2] , given: 222

Re: Six computers, each working at the same constant rate, together can [#permalink]

Show Tags

New post 13 Mar 2011, 10:45
2
This post received
KUDOS
Expert's post
3
This post was
BOOKMARKED
n2739178 wrote:

...WHAT I DON'T GET, is this business about "90 computer days"... is there another way to solve it? I wouldn't have known at all to solve it the way they solved it


Number of computers and days taken have an inverse relation. i.e. if number of computers increase, days taken will reduce... Agreed?

If to complete the work in 15 days, you need 6 computers,
then to complete the work in 1 day, how many computers will you need?
You will need more computers now so you multiply 15 by 6 i.e. 15*6 = 90 computers.

To complete the work in 1 day, you need 90 computers.
To complete the work in 10 days, how many computers will you need? You will need fewer computers now, right? So you divide 90 by 10 to get 90/10 = 9 computers. You need 3 extra computers.

Another way:
15 days .................. 6 computers
10 days ...................? computers
Unknown is the number of computers. You need to change the previous number of computers to get the new number. You will need to multiply either by 15/10 or 10/15. If you have fewer number of days, you will need more computers so you multiply by 15/10 (i.e. greater than 1) to give a bigger number
6*(15/10) = 9

Another way:
Days (d) and computers (c) are inversely proportional.
dc = k (a constant)
Say x is the new number of computers.
15*6 = k
10*x = k
15*6 = 10*x
x = 9

Finally, the given explanation way:
6 computers need 15 days. This means each computer is working for 15 days. How much total work is there? Work which needs 6 computers working simultaneously for 15 days so 15+15+15+15+15+15 = 90 days will be needed if only 1 computer were working.
Now, if we need to finish the total work in 10 days, how many computers do we need? 10 + 10 + 10 ..... = 90
We will need 9 such computers to finish the given work.
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

Director
Director
User avatar
Status: No dream is too large, no dreamer is too small
Joined: 14 Jul 2010
Posts: 650
Followers: 42

Kudos [?]: 834 [0], given: 39

Re: Six computers, each working at the same constant rate, together can [#permalink]

Show Tags

New post 13 Mar 2011, 11:33
1
This post was
BOOKMARKED
To complete in 15 days 6 computers required
so '' 10 = 6*15/10 = 9
so additional 3 computers required.
Ans A.
_________________

Collections:-
PSof OG solved by GC members: http://gmatclub.com/forum/collection-ps-with-solution-from-gmatclub-110005.html
DS of OG solved by GC members: http://gmatclub.com/forum/collection-ds-with-solution-from-gmatclub-110004.html
100 GMAT PREP Quantitative collection http://gmatclub.com/forum/gmat-prep-problem-collections-114358.html
Collections of work/rate problems with solutions http://gmatclub.com/forum/collections-of-work-rate-problem-with-solutions-118919.html
Mixture problems in a file with best solutions: http://gmatclub.com/forum/mixture-problems-with-best-and-easy-solutions-all-together-124644.html

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 12888
Followers: 561

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

Premium Member
Re: Six computers, each working at the same constant rate, together can [#permalink]

Show Tags

New post 20 May 2016, 13:02
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

Math Forum Moderator
User avatar
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 2115
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
Followers: 82

Kudos [?]: 558 [0], given: 311

GMAT ToolKit User Premium Member CAT Tests
Re: Six computers, each working at the same constant rate, together can [#permalink]

Show Tags

New post 21 May 2016, 10:08
n2739178 wrote:
Six computers, each working at the same constant rate, together can process a certain amount of data in 15 days. How many additional computers, each working at the same constant rate, will be needed to process the same amount of data in 10 days?

(A) 3
(B) 5
(C) 6
(D) 9
(E) 12


Total work = Computer * Days
Total work = 15 * 6 => 90

Quote:
How many additional computers, each working at the same constant rate, will be needed to process the same amount of data in 10 days?


Total work = Computer * Days

90 = Computer * 10

So, Total computers required is 9

So, additional computers required is 3 ( 9 - 6 )

So, Correct answer will be (A)
_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Manager
Manager
User avatar
Joined: 17 May 2016
Posts: 67
Concentration: Finance, International Business
GMAT 1: 720 Q49 V39
GPA: 3.7
WE: Analyst (Investment Banking)
Followers: 4

Kudos [?]: 41 [0], given: 105

Six computers, each working at the same constant rate, together can [#permalink]

Show Tags

New post 31 May 2016, 02:25
6 computers do work in 15 days, or they do \(\frac{1}{15}\) of the job per day together
Thus one computer does \(\frac{1}{15} * \frac{1}{6}\) = \(\frac{1}{90}\) per day

How many computers would we need in total to complete the job in 10 days?

1/ \(\frac{1}{90}\) * X = 10 days
\(\frac{90}{X}\) = 10 days
90 = 10X
X = 9

In total we need 9 computers to complete the work. Since we already have 6, we need extra 3.
_________________

Please kindly +Kudos if my posts or questions help you!

My debrief: Self-study: How to improve from 620(Q39,V36) to 720(Q49,V39) in 25 days!

Senior Manager
Senior Manager
avatar
Joined: 20 Feb 2015
Posts: 389
Concentration: Strategy, General Management
Followers: 2

Kudos [?]: 58 [0], given: 10

Re: Six computers, each working at the same constant rate, together can [#permalink]

Show Tags

New post 31 May 2016, 04:39
let the total work be 1

now,
1 work is done in 6*15 computer days = 90 computer days
same work has to be done in x*10 computer days.
Therefore,

6*15=x*10
x=9

additional computers = 3
Intern
Intern
avatar
Joined: 16 Jul 2016
Posts: 10
Followers: 0

Kudos [?]: 2 [0], given: 1

Six computers, each working at the same constant rate, together can [#permalink]

Show Tags

New post 02 Aug 2016, 20:21
Once you see enough of these problems you realize perhaps the most efficient way to solve them is to set up a simple multiplication equation.

\(6(15)=10(x)\).

\(90=10x\)

\(9=x.\)

Be careful, to answer the question we must attend to additional hours. The answer is \(9-6=3\).

This issue could be bypassed by setting up this equation. \(6(15)=(6+x)(10)\)

Dividing both sides by 2(5) we obtain \(9=6+x\)

\(Hence, x=3\)
Six computers, each working at the same constant rate, together can   [#permalink] 02 Aug 2016, 20:21
    Similar topics Author Replies Last post
Similar
Topics:
10 Experts publish their posts in the topic Three medical experts, working together at the same constant rate, can Bunuel 7 12 Nov 2014, 09:18
104 Experts publish their posts in the topic Six machines, each working at the same constant rate srkaleem 21 05 Feb 2012, 22:28
9 While working alone at their constant rates computer X can process 240 Baten80 12 29 Mar 2011, 03:36
27 Experts publish their posts in the topic Each of 10 machines works at the same constant rate doing a gsaxena26 16 12 Jun 2010, 09:50
15 Experts publish their posts in the topic Six machines, each working at the same constant rate zz0vlb 18 26 Apr 2010, 20:53
Display posts from previous: Sort by

Six computers, each working at the same constant rate, together can

  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®.