Author 
Message 
TAGS:

Hide Tags

Manager
Joined: 28 May 2009
Posts: 154
Location: United States
Concentration: Strategy, General Management
GMAT Date: 03222013
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, 16:04
1
This post received KUDOS
5
This post was BOOKMARKED
Question Stats:
75% (01:06) correct 25% (01:32) wrong based on 205 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
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
New to GMAT Club? Start here
Kindle Flashcards  Quant (Official Gmat Club, miguemick's Quant topics), and Verbal (Official Gmat Club)  in Kindle (azw3) format



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 7955
Location: Pune, India

Re: A company has two models of computers, model M and model N [#permalink]
Show Tags
05 Feb 2013, 20:29
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 Answer (C) There are only two things to remember in work rate questions: 1. Rates are Additive. 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



VP
Joined: 02 Jul 2012
Posts: 1212
Location: India
Concentration: Strategy
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, 21:43
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 Answer is C
_________________
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



Math Expert
Joined: 02 Sep 2009
Posts: 43891

Re: A company has two models of computers, model M and model N [#permalink]
Show Tags
05 Feb 2013, 23:56
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: acompanyhastwotypesofmachinestyperandtypes130108.html
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Intern
Joined: 14 Mar 2013
Posts: 48
Location: United States
Concentration: General Management, Leadership
GMAT Date: 12032013
WE: General Management (Retail)

Re: A company has two models of computers, model M and model N [#permalink]
Show Tags
23 Nov 2013, 04:19
1
This post received 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  Please +KUDOS if you like my answer.



NonHuman User
Joined: 09 Sep 2013
Posts: 13792

Re: A company has two models of computers, model M and model N [#permalink]
Show Tags
27 Feb 2017, 04:30
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.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources



Target Test Prep Representative
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2016

Re: A company has two models of computers, model M and model N [#permalink]
Show Tags
01 Mar 2017, 17:20
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 Answer: C
_________________
Jeffery Miller
Head of GMAT Instruction
GMAT Quant SelfStudy Course
500+ lessons 3000+ practice problems 800+ HD solutions



Director
Joined: 07 Dec 2014
Posts: 907

Re: A company has two models of computers, model M and model N [#permalink]
Show Tags
02 Mar 2017, 11:16
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*1/6*1 minute=1 task c=6 pairs=6 model M computers




Re: A company has two models of computers, model M and model N
[#permalink]
02 Mar 2017, 11:16






