It is currently 23 Nov 2017, 06:18

### 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

# A company has two models of computers, model M and model N

Author Message
TAGS:

### Hide Tags

Manager
Joined: 28 May 2009
Posts: 155

Kudos [?]: 267 [1], given: 91

Location: United States
Concentration: Strategy, General Management
GMAT Date: 03-22-2013
GPA: 3.57
WE: Information Technology (Consulting)
A company has two models of computers, model M and model N [#permalink]

### Show Tags

05 Feb 2013, 17:04
1
KUDOS
4
This post was
BOOKMARKED
00:00

Difficulty:

25% (medium)

Question Stats:

74% (01:06) correct 26% (01:32) wrong based on 202 sessions

### HideShow timer Statistics

A company has two models of computers, model M and model N. Operating at a constant rate, a model M computer can complete a certain task in 18 minutes and a model N computer can complete the same task in 9 minutes. If the company used the same number of each model of computer to complete the task in 1 minute, how many model M computers were used?

(A) 2

(B) 3

(C) 6

(D) 9

(E) 12

Source: Gmat Hacks 1800
[Reveal] Spoiler: OA

_________________

Kudos [?]: 267 [1], given: 91

Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 7747

Kudos [?]: 17858 [4], given: 235

Location: Pune, India
Re: A company has two models of computers, model M and model N [#permalink]

### Show Tags

05 Feb 2013, 21:29
4
KUDOS
Expert's post
megafan wrote:
A company has two models of computers, model M and model N. Operating at a constant rate, a model M computer can complete a certain task in 18 minutes and a model N computer can complete the same task in 9 minutes. If the company used the same number of each model of computer to complete the task in 1 minute, how many model M computers were used?

(A) 2

(B) 3

(C) 6

(D) 9

(E) 12

Source: Gmat Hacks 1800

Time taken by model M computer to complete 1 work = 18 mins so Rate of work of model M = 1/18 work/min
Time taken by model N computer to complete 1 work = 9 mins so Rate of work of model N = 1/9 work/min

1 work was completed in 1 min so combined rate of work of x computers of M type and x computers of N type = 1 work/min
(because Work = Rate*Time)

x/18 + x/9 = 1 (Rates are additive)
x = 6

There are only two things to remember in work rate questions:
2. Work = Rate*Time
(which implies Rate = 1/Time)
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for \$199

Veritas Prep Reviews

Kudos [?]: 17858 [4], given: 235

VP
Joined: 02 Jul 2012
Posts: 1216

Kudos [?]: 1696 [0], given: 116

Location: India
Concentration: Strategy
GMAT 1: 740 Q49 V42
GPA: 3.8
WE: Engineering (Energy and Utilities)
Re: A company has two models of computers, model M and model N [#permalink]

### Show Tags

05 Feb 2013, 22:43
megafan wrote:
A company has two models of computers, model M and model N. Operating at a constant rate, a model M computer can complete a certain task in 18 minutes and a model N computer can complete the same task in 9 minutes. If the company used the same number of each model of computer to complete the task in 1 minute, how many model M computers were used?

(A) 2

(B) 3

(C) 6

(D) 9

(E) 12

Source: Gmat Hacks 1800

Let's say 1 work is processing 18 gb of data.

Model M : 1 gb per min

Model N : 2 gb per min

Working together, 1 M and 1 N = 3 gb per min

So, 6 times as many computers would work at 18 gb per min.

So no. of M = 6

_________________

Did you find this post helpful?... Please let me know through the Kudos button.

Thanks To The Almighty - My GMAT Debrief

GMAT Reading Comprehension: 7 Most Common Passage Types

Kudos [?]: 1696 [0], given: 116

Math Expert
Joined: 02 Sep 2009
Posts: 42326

Kudos [?]: 133106 [0], given: 12411

Re: A company has two models of computers, model M and model N [#permalink]

### Show Tags

06 Feb 2013, 00:56
megafan wrote:
A company has two models of computers, model M and model N. Operating at a constant rate, a model M computer can complete a certain task in 18 minutes and a model N computer can complete the same task in 9 minutes. If the company used the same number of each model of computer to complete the task in 1 minute, how many model M computers were used?

(A) 2

(B) 3

(C) 6

(D) 9

(E) 12

Source: Gmat Hacks 1800

Another copied question from Gmat hacks. Original question from GMAT Prep:

Quote:
A company has two types of machines, type R and type S. Operating at a constant rate, a machine of type R does a certain job in 36 hrs and a machine of type S does the same job in 18 hours. If the company used the same number of each type of machine to do the job in 2 hours, how many machines of type R were used?

A. 3
B. 4
C. 6
D. 9
E. 12

Discussed here: a-company-has-two-types-of-machines-type-r-and-type-s-130108.html
_________________

Kudos [?]: 133106 [0], given: 12411

Intern
Joined: 14 Mar 2013
Posts: 48

Kudos [?]: 69 [1], given: 119

Location: United States
GMAT Date: 12-03-2013
WE: General Management (Retail)
Re: A company has two models of computers, model M and model N [#permalink]

### Show Tags

23 Nov 2013, 05:19
1
KUDOS
M = 1 job in 18 min → 1/18
N = 1 job in 09 min → 1/9

M+N = 1/18 + 1/9 = 3/18 = 1/6

M+N = 1 job in 6 minutes.

To complete the job in 1 min will be necessary 6 M+N.

Ans C

-------------

Kudos [?]: 69 [1], given: 119

Non-Human User
Joined: 09 Sep 2013
Posts: 15524

Kudos [?]: 283 [0], given: 0

Re: A company has two models of computers, model M and model N [#permalink]

### Show Tags

27 Feb 2017, 05:30
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.
_________________

Kudos [?]: 283 [0], given: 0

Target Test Prep Representative
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 1713

Kudos [?]: 915 [1], given: 5

Re: A company has two models of computers, model M and model N [#permalink]

### Show Tags

01 Mar 2017, 18:20
1
KUDOS
Expert's post
megafan wrote:
A company has two models of computers, model M and model N. Operating at a constant rate, a model M computer can complete a certain task in 18 minutes and a model N computer can complete the same task in 9 minutes. If the company used the same number of each model of computer to complete the task in 1 minute, how many model M computers were used?

(A) 2

(B) 3

(C) 6

(D) 9

(E) 12

We are given that the model M computer can complete a task in 18 minutes; thus the rate of model M is 1/18. We are also given that a model N computer can complete the same task in 9 minutes; thus the rate of model N is 1/9.

We need to determine the number of each model of computer used if the task were completed in 1 minute. If that is the case, then the combined rate of all the computers is 1/1 = 1. We can let n = the number of computers used for each model of computer and create the following equation:

rate of n model M computers + rate of n model N computers = 1

n(1/18) + n(1/9) = 1

Multiplying the entire equation by 18, we have:

n + 2n = 18

3n = 18

n = 6

_________________

Jeffery Miller

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Kudos [?]: 915 [1], given: 5

Director
Joined: 07 Dec 2014
Posts: 839

Kudos [?]: 272 [0], given: 15

Re: A company has two models of computers, model M and model N [#permalink]

### Show Tags

02 Mar 2017, 12:16
megafan wrote:
A company has two models of computers, model M and model N. Operating at a constant rate, a model M computer can complete a certain task in 18 minutes and a model N computer can complete the same task in 9 minutes. If the company used the same number of each model of computer to complete the task in 1 minute, how many model M computers were used?

(A) 2

(B) 3

(C) 6

(D) 9

(E) 12

Source: Gmat Hacks 1800

let c=number of pairs
combined rate=1/6
c=6 pairs=6 model M computers

Kudos [?]: 272 [0], given: 15

Re: A company has two models of computers, model M and model N   [#permalink] 02 Mar 2017, 12:16
Display posts from previous: Sort by