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

It is currently 15 Sep 2014, 16:56

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

Machine M can produce x units in 3/4 of the time it takes

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 11 Nov 2006
Posts: 144
Followers: 1

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

Machine M can produce x units in 3/4 of the time it takes [#permalink] New post 02 May 2007, 08:54
Machine M can produce x units in 3/4 of the time it takes machine N to produce x units. Machine N can produce x units in 2/3 the time it takes machine O to produce x units. If all three machines are working simultaneously, what fraction of the total output is produced by machine N?
(A) 1/2
(B) 1/3
(C) 4/13
(D) 8/29
(E) 6/33


Please solve it and explain it... thanks!
Senior Manager
Senior Manager
avatar
Joined: 11 Jun 2006
Posts: 254
Followers: 3

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

GMAT Tests User
 [#permalink] New post 02 May 2007, 12:44
Use machine O as a starting point since it is the slowest machine, all other machines will be a fraction of O.

Time of M = 3/4 * 2/3 = 6/12
Time of N = 2/3 * 4/4 = 8/12
Time of O = 12/12

The recipricol of the times stated above = the rates; since rates are additive, add...

M + N + O = 9/2

Putting N over the total:

3/2 / 9/2 = 1/3

Answer (B)
Senior Manager
Senior Manager
User avatar
Joined: 24 Nov 2006
Posts: 352
Followers: 1

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

GMAT Tests User
Re: Machines M, N and O [#permalink] New post 02 May 2007, 17:14
M N O
----------------------------
t/2 2t/3 t (How long it takes each to produce x)

In t: 2x 3x/2 x (How much they produce in t (hs, secs, etc))

What fraction of total output is produced by N? (3x/2)/(2x+3x/2+x) = 1/3 => B.

Last edited by Andr359 on 11 May 2007, 13:25, edited 1 time in total.
Manager
Manager
User avatar
Joined: 28 Dec 2006
Posts: 62
Followers: 1

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

 [#permalink] New post 02 May 2007, 18:14
Is the answer C?

let o=12 hence n=8 and m = 6.

Total hours =26
n=8

Therefore fraction =8/26 =4/13
Manager
Manager
avatar
Joined: 02 May 2007
Posts: 155
Followers: 1

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

GMAT Tests User
Re: Machines M, N and O [#permalink] New post 02 May 2007, 20:27
querio wrote:
Machine M can produce x units in 3/4 of the time it takes machine N to produce x units. Machine N can produce x units in 2/3 the time it takes machine O to produce x units. If all three machines are working simultaneously, what fraction of the total output is produced by machine N?
(A) 1/2
(B) 1/3
(C) 4/13
(D) 8/29
(E) 6/33


Please solve it and explain it... thanks!


(B) it is

M = time for M to produce the total output T:
=> T/M = output M produce in 01 unit of time
M = 3/4N
N = time for N to produce the total output T:
=> T/N = output N produce in 01 unit of time
N = 3/4O
O = time for O to produce the total output T

Output the 03 machines produce in 01 unit of time = T/M + T/N + T/O = T/(3/4N) + T/N + T(3N/2) = 3T/N

Fraction of the total output is produced by machine N = (T/N)/3T/N = 1/3

Last edited by kirakira on 02 May 2007, 21:03, edited 1 time in total.
Manager
Manager
avatar
Joined: 17 Apr 2007
Posts: 93
Followers: 1

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

 [#permalink] New post 02 May 2007, 20:57
B - 1/3

Let say it takes T time for O to produce 1 unit -> rate of work 1/T
N's rate of work 1/(2/3 * T) = 3/2T
M's rate of work - 1/(2/3 * 3/4 T) = 2/T

so total rate of work - 1/T + 3/2T + 2/T = 9/2T

N's part is (3/2T) / (9/2T) = 1/3
Manager
Manager
avatar
Joined: 04 Oct 2006
Posts: 78
Followers: 1

Kudos [?]: 6 [0], given: 0

 [#permalink] New post 03 May 2007, 00:20
- time it takes machine O to do the job = t
- time it takes machine N to do the job = 2t/3
- time it takes machine M to do the job = 3/4 * 2/3 * t = t/2


In one hour O+N+M do 1/t + 3/2t + 2/t = 9/2t of the job.

In one hour N do (3/2t) / (9/2t) = 1/3 of the job.

Answer B.
Manager
Manager
avatar
Joined: 11 Nov 2006
Posts: 144
Followers: 1

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

 [#permalink] New post 03 May 2007, 03:27
[b]OA[/b] is B

thanks!
VP
VP
User avatar
Joined: 08 Jun 2005
Posts: 1157
Followers: 6

Kudos [?]: 113 [0], given: 0

GMAT Tests User
 [#permalink] New post 03 May 2007, 11:59
baer wrote:
Use machine O as a starting point since it is the slowest machine, all other machines will be a fraction of O.

Time of M = 3/4 * 2/3 = 6/12
Time of N = 2/3 * 4/4 = 8/12
Time of O = 12/12

The recipricol of the times stated above = the rates; since rates are additive, add...

M + N + O = 9/2

Putting N over the total:

3/2 / 9/2 = 1/3

Answer (B)


can you please explain why 4/4 ?
Senior Manager
Senior Manager
avatar
Joined: 11 Jun 2006
Posts: 254
Followers: 3

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

GMAT Tests User
 [#permalink] New post 03 May 2007, 12:56
KillerSquirrel wrote:
baer wrote:
Use machine O as a starting point since it is the slowest machine, all other machines will be a fraction of O.

Time of M = 3/4 * 2/3 = 6/12
Time of N = 2/3 * 4/4 = 8/12
Time of O = 12/12

The recipricol of the times stated above = the rates; since rates are additive, add...

M + N + O = 9/2

Putting N over the total:

3/2 / 9/2 = 1/3

Answer (B)


can you please explain why 4/4 ?


Just to get a common denominator of 12, so that you can add up the rates in the next step. I was just showing the logic of the problem.
  [#permalink] 03 May 2007, 12:56
    Similar topics Author Replies Last post
Similar
Topics:
12 Experts publish their posts in the topic Machine M, working alone at its constant rate, produces x wi violetsplash 5 24 Sep 2013, 07:29
1 Experts publish their posts in the topic If Machine X can produce 80 widgets in 4 hours guerrero25 3 27 Aug 2013, 00:27
14 Experts publish their posts in the topic Machine M, N, O working simultaneously Machine M can produce MBAhereIcome 8 26 Aug 2011, 06:30
11 Experts publish their posts in the topic Machine X takes 20 hours longer than machine Y to produce 10 rxs0005 9 02 Mar 2011, 14:23
Machine M can produce x units in 3/4 of the time it takes ggarr 4 03 Jun 2007, 16:34
Display posts from previous: Sort by

Machine M can produce x units in 3/4 of the time it takes

  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®.