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

 It is currently 03 Sep 2015, 11:25

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Machines x and y work at their respective constant rates.

Author Message
Intern
Joined: 19 Jun 2009
Posts: 29
Followers: 0

Kudos [?]: 38 [0], given: 1

Machines x and y work at their respective constant rates. [#permalink]  17 Oct 2009, 12:32
00:00

Difficulty:

(N/A)

Question Stats:

25% (00:00) correct 75% (02:39) wrong based on 5 sessions
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Machines x and y work at their respective constant rates. how many more hours does it take machine y, working alone, to fill ta production order of a certain size than it dtakes machine x, working alone?

) machines x and y working together, fill a production order of this size in two thirds the time that machine x, working aloe, does.

2) machine y, working alone, fills a production order of this size in twice the time that machine x, working alone, does

please provide a detailed explanation. thanks.
Math Expert
Joined: 02 Sep 2009
Posts: 29205
Followers: 4750

Kudos [?]: 50256 [0], given: 7540

Re: machines x and y [#permalink]  17 Oct 2009, 13:22
Expert's post
Machines X and Y work at their respective constant rates. How many more hours does it take machine Y, working alone, to fill a production order of a certain size than it takes machine X, working alone?

Let $$x$$ and $$y$$ be the times needed for machines X and Y respectively working alone to fill a production order of this size.

Question: $$y-x=?$$

(1) Machines X and Y, working together, fill a production order of this size in 2/3 the time that machine X, working alone, does --> general relationship: $$\frac{1}{x}+\frac{1}{y}=\frac{1}{total \ time}$$ --> Total time needed for machines X and Y working together is $$total \ time=\frac{xy}{x+y}$$ (general formula) --> given $$\frac{xy}{x+y}=x*\frac{2}{3}$$ --> $$2x=y$$. Not sufficient

(2) Machine Y, working alone, fills a production order of this size in twice the time that machine X, working alone, does --> $$2x=y$$, the same info. Not sufficient

(1)+(2) Nothing new. Not Sufficient.

Hope it helps.
_________________
Senior Manager
Joined: 23 May 2008
Posts: 428
Followers: 4

Kudos [?]: 166 [0], given: 14

Tough DS [#permalink]  12 Dec 2009, 07:51
Hi please tell the approach to solve this question
Attachments

DS-3.jpg [ 143.42 KiB | Viewed 1459 times ]

Intern
Status: Applying
Joined: 14 Oct 2009
Posts: 31
Location: California
Schools: Cornell AMBA, Kellogg, Oxford, Cambridge
Followers: 0

Kudos [?]: 36 [0], given: 4

Re: Tough DS [#permalink]  12 Dec 2009, 11:52
The question stem is asking "y is how much more than x"
i.e. how much is z in "y = x + z"
As explained by Bunuel, the two statements provide y=zx i.e how many times x is y.
Hence, both statements are not sufficient.
Manager
Joined: 26 Nov 2009
Posts: 176
Followers: 3

Kudos [?]: 53 [0], given: 5

Math (DS) [#permalink]  13 Dec 2009, 04:11
Machine X and Y work at respective constant rates.How many more hours does it take machine Y,working alone ,to fill a production order of certain size than it takes machine X, working alone ?

1.Machine X and Machine Y working together, fill production order of this size in two-thirds the time that Machine X,working alone does.

2.Machine Y,working alone ,fills a production order of this size in twice the time that machine X ,working alone,does
[Reveal] Spoiler:
E
Manager
Joined: 09 May 2009
Posts: 202
Followers: 1

Kudos [?]: 144 [0], given: 13

Re: Tough DS [#permalink]  14 Dec 2009, 08:29
gurpreet07 wrote:
Hi please tell the approach to solve this question

IMO E

as the q is asking exactly how many hrs and we are getting ty=2tx hence none of the statements are suff.
_________________

GMAT is not a game for losers , and the moment u decide to appear for it u are no more a loser........ITS A BRAIN GAME

Re: Tough DS   [#permalink] 14 Dec 2009, 08:29
Display posts from previous: Sort by