It is currently 19 Sep 2017, 12:02

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

Running at their respective constant rates, machine X takes

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Senior Manager
Senior Manager
avatar
Joined: 05 Jun 2008
Posts: 304

Kudos [?]: 169 [0], given: 0

Running at their respective constant rates, machine X takes [#permalink]

Show Tags

New post 24 Sep 2008, 07:40
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 1 sessions

HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Running at their respective constant rates, machine X takes 2 days longer to produce w
widgets than machine Y. At these rates, if the two machines together produce 5/4 w
widgets in 3 days, how many days would it take machine X alone to produce 2w widgets?
A. 4
B. 6
C. 8
D. 10
E. 12

Kudos [?]: 169 [0], given: 0

Manager
Manager
User avatar
Joined: 20 Mar 2008
Posts: 158

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

Location: USA
Re: PS-Work Problem [#permalink]

Show Tags

New post 24 Sep 2008, 10:22
y takes n days for W widgets Per day -> 1/n
x takes n+2 days W widgets Per day -> 1/n+2

Together these produce 5/4 W widgets in 3 days or 5/12 W per day

Per Day Rate of y + Per day rate of x = 5/12 W
1/n + 1/n+2 = 5/12 W

n=4 satisfies this ( No of days Y takes to produce W)

We have couple of more steps for the answer

No of days X takes is n+2 = 6
For 2W =12

E

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

Director
Director
avatar
Joined: 23 May 2008
Posts: 803

Kudos [?]: 82 [0], given: 0

Re: PS-Work Problem [#permalink]

Show Tags

New post 24 Sep 2008, 16:40
Quote:
Per Day Rate of y + Per day rate of x = 5/12 W
1/n + 1/n+2 = 5/12 W

n=4 satisfies this ( No of days Y takes to produce W)


can you go through the steps you did to get to n=4? I ended up factoring the quadratic equation to get 4 as a possible n, but this method took forever

Kudos [?]: 82 [0], given: 0

Manager
Manager
User avatar
Joined: 20 Mar 2008
Posts: 158

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

Location: USA
Re: PS-Work Problem [#permalink]

Show Tags

New post 25 Sep 2008, 09:23
bigtreezl wrote:
Quote:
Per Day Rate of y + Per day rate of x = 5/12 W
1/n + 1/n+2 = 5/12 W

n=4 satisfies this ( No of days Y takes to produce W)


can you go through the steps you did to get to n=4? I ended up factoring the quadratic equation to get 4 as a possible n, but this method took forever



When I wrote the original explanation i plugged in couple of numbers to test where n would satisfy the equation and got to 4 .... did not do this calculation. However, this may be counterproductive at times. There is no sure shot way that I am aware of ... we need to go through the lengthy process of solving the quadratic equation.

I forgot to put W on LHS in the original explanation... taking W off from both sides

1/n + 1/n+2 = 5/12

2n+2/ n^2+2n= 5/12

5n^2- 14n -24 =0

5n^2- 20n + 6n -24 =0

5n( n-4) + 6 (n-4)=0

(5n+6)(n-4)=0

n=-6/5 or n=4... by eliminating -ve.. we get n=4

I know that you have done this already but for the completeness of this topic, I am putting the steps here.

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

Re: PS-Work Problem   [#permalink] 25 Sep 2008, 09:23
Display posts from previous: Sort by

Running at their respective constant rates, machine X takes

  post reply Question banks Downloads My Bookmarks Reviews Important topics  


cron

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®.