Find all School-related info fast with the new School-Specific MBA Forum

It is currently 21 Sep 2014, 20:15

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

How to solve?

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
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 [?]: 29 [0], given: 12

How to solve? [#permalink] New post 13 Mar 2011, 09:10
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

90% (01:42) correct 10% (00:00) wrong based on 10 sessions
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
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 [?]: 29 [0], given: 12

Re: How to solve? [#permalink] 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
1 KUDOS received
Veritas Prep GMAT Instructor
User avatar
Joined: 16 Oct 2010
Posts: 4780
Location: Pune, India
Followers: 1120

Kudos [?]: 5084 [1] , given: 164

Re: How to solve? [#permalink] New post 13 Mar 2011, 10:45
1
This post received
KUDOS
Expert's post
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

Save $100 on Veritas Prep GMAT Courses And Admissions Consulting
Enroll now. Pay later. Take advantage of Veritas Prep's flexible payment plan options.

Veritas Prep Reviews

Director
Director
User avatar
Status: GMAT Learner
Joined: 14 Jul 2010
Posts: 652
Followers: 34

Kudos [?]: 231 [0], given: 32

GMAT Tests User
Re: How to solve? [#permalink] New post 13 Mar 2011, 11:33
To complete in 15 days 6 computers required
so '' 10 = 6*15/10 = 9
so additional 3 computers required.
Ans A.
_________________

I am student of everyone-baten
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

Re: How to solve?   [#permalink] 13 Mar 2011, 11:33
    Similar topics Author Replies Last post
Similar
Topics:
1 Experts publish their posts in the topic How to solve? n2739178 3 13 Mar 2011, 09:10
How to solve? SoniaSaini 3 25 Jan 2011, 20:37
How to solve ? samrand 1 15 Jan 2010, 05:14
How to solve Work questions andy_gr8 3 01 Dec 2005, 22:04
SC- how to solve this? jennygmat 0 24 Mar 2005, 19:03
Display posts from previous: Sort by

How to solve?

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| 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®.