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A company has two models of computers, model M and model N
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05 Feb 2013, 16:04
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74% (01:34) correct 26% (01:44) wrong based on 232 sessions
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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
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Re: A company has two models of computers, model M and model N
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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)
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Re: A company has two models of computers, model M and model N
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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
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Re: A company has two models of computers, model M and model N
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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
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Re: A company has two models of computers, model M and model N
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23 Nov 2013, 04:19
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.



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



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Re: A company has two models of computers, model M and model N
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20 Jun 2018, 15:06
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