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• ### $450 Tuition Credit & Official CAT Packs FREE November 15, 2018 November 15, 2018 10:00 PM MST 11:00 PM MST EMPOWERgmat is giving away the complete Official GMAT Exam Pack collection worth$100 with the 3 Month Pack ($299) • ### Free GMAT Strategy Webinar November 17, 2018 November 17, 2018 07:00 AM PST 09:00 AM PST Nov. 17, 7 AM PST. Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT. # Working at their respective constant rates, machine A makes  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics Author Message TAGS: ### Hide Tags Manager Joined: 10 Feb 2011 Posts: 108 Working at their respective constant rates, machine A makes [#permalink] ### Show Tags 09 Mar 2011, 14:03 2 18 00:00 Difficulty: 95% (hard) Question Stats: 36% (02:11) correct 64% (02:13) wrong based on 420 sessions ### HideShow timer Statistics Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 100 copies in 15 minutes. If a number of x machine A and a number of y machine B work simultaneously at their respective rates for 2 hours, what is the total number of copies that they will produce? (1) x = y. (2) 5x + 4y = 90. ##### Most Helpful Community Reply Manager Joined: 14 Feb 2011 Posts: 175 Re: Working at their respective constant rates, machine A makes [#permalink] ### Show Tags 09 Mar 2011, 22:56 3 4 banksy wrote: 268. Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 100 copies in 15 minutes. If a number of x machine A and a number of y machine B work simultaneously at their respective rates for 2 hours, what is the total number of copies that they will produce? (1) x = y. (2) 5x + 4y = 90. Rate of Machine A is 100/12 copies per minute and that of Machine Y is 100/15 copies per minute. When x number of A machines and y number of B machines work simultaneously at their respective rates for 2 hours (120 minutes), they will produce $$120*((100/12)*x+(100/15)*y)$$copies $$120*((100/12)*x+(100/15)*y)$$ on simplification becomes $$200*(5x+4y)$$ Statement 1 says $$x=y$$, which doesn't help us get the exact numbers, so insufficient Statement 2 says $$5x+4y = 90$$, we cant solve for x and y from this, but all we need to answer the question is value of 5x+4y which we get from this statement, so sufficient. Answer B. ##### General Discussion Intern Status: Sophomore Affiliations: President of Student Associoation Joined: 09 Dec 2010 Posts: 35 Schools: HBS 2+2, IESE YTP Re: Working at their respective constant rates, machine A makes [#permalink] ### Show Tags 09 Mar 2011, 16:00 banksy wrote: 268. Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 100 copies in 15 minutes. If a number of x machine A and a number of y machine B work simultaneously at their respective rates for 2 hours, what is the total number of copies that they will produce? (1) x = y. (2) 5x + 4y = 90. can't find the the total copies that they will produce without knowing the value of x and y. So with (1) and (2), it is sufficient to find values. Answer C. Retired Moderator Joined: 16 Nov 2010 Posts: 1429 Location: United States (IN) Concentration: Strategy, Technology Re: Working at their respective constant rates, machine A makes [#permalink] ### Show Tags 09 Mar 2011, 23:03 1 (1) is clearly insufficient. For (2), several answers are possible: 5 * 14 + 4 * 5 = 90 5 * 10 + 4 * 8 = 90 But (1) and (2) together give x = y = 10, so answer is C _________________ Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant) GMAT Club Premium Membership - big benefits and savings Manager Joined: 14 Feb 2011 Posts: 175 Re: Working at their respective constant rates, machine A makes [#permalink] ### Show Tags 09 Mar 2011, 23:11 1 Mongolia2HBS wrote: banksy wrote: 268. Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 100 copies in 15 minutes. If a number of x machine A and a number of y machine B work simultaneously at their respective rates for 2 hours, what is the total number of copies that they will produce? (1) x = y. (2) 5x + 4y = 90. can't find the the total copies that they will produce without knowing the value of x and y. So with (1) and (2), it is sufficient to find values. Answer C. subhashghosh wrote: (1) is clearly insufficient. For (2), several answers are possible: 5 * 14 + 4 * 5 = 90 5 * 10 + 4 * 8 = 90 But (1) and (2) together give x = y = 10, so answer is C Guys, we are not concerned here with exact values of x and y. All we need to find is the total number of copies the machines working together would produce. So, anything that gives us their combined relationship is sufficient. Statement 2 effectively is telling us about that relationship. So, statement B is sufficient to answer the given question. Irrespective of whatever value x and y individually may have, as long as 5x+4y is 90, the number of pages they will produce would remain 200*90 We can easily check the same by putting different values for x and y. Intern Joined: 06 Sep 2010 Posts: 31 Re: Working at their respective constant rates, machine A makes [#permalink] ### Show Tags 10 Mar 2011, 07:30 As per question: A makes 1000 pages in 2 hours B makes 800 pages in 2 hours x machines of A and y machines of B are used. Total output = 1000x + 800y......(1) Given by statement 2: 5x + 4y = 90...........(2) From 1 and 2, The answer will be 90 * 200 = 1800 pages. Hence B alone is sufficient. Director Status: Impossible is not a fact. It's an opinion. It's a dare. Impossible is nothing. Affiliations: University of Chicago Booth School of Business Joined: 03 Feb 2011 Posts: 748 Re: Working at their respective constant rates, machine A makes [#permalink] ### Show Tags 10 Mar 2011, 19:45 A "lone wolf" trap. Intern Status: Sophomore Affiliations: President of Student Associoation Joined: 09 Dec 2010 Posts: 35 Schools: HBS 2+2, IESE YTP Re: Working at their respective constant rates, machine A makes [#permalink] ### Show Tags 11 Mar 2011, 22:24 I was wrong, B alone is sufficient. Thanks to beyondgmatscore and pesfunk. Intern Joined: 22 Oct 2015 Posts: 17 Re: Working at their respective constant rates, machine A makes [#permalink] ### Show Tags 04 Feb 2016, 13:35 Rate of A $$\frac{100}{12}$$ Rate of B $$\frac{100}{15}]$$ $$\frac{100x}{12}*120 + \frac{100y}{15}*120$$ $$1000x + 800y$$ 1. x=y Tell us nothing about the actual values. 2. 5x + 4y = 90 $$1000x + 800y$$ $$(5x+4y=90)*200$$ $$1000x+800y=18000$$ Intern Status: One more try Joined: 01 Feb 2015 Posts: 43 Location: India Concentration: General Management, Economics WE: Corporate Finance (Commercial Banking) Re: Working at their respective constant rates, machine A makes [#permalink] ### Show Tags 13 Feb 2016, 21:05 banksy wrote: Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 100 copies in 15 minutes. If a number of x machine A and a number of y machine B work simultaneously at their respective rates for 2 hours, what is the total number of copies that they will produce? (1) x = y. (2) 5x + 4y = 90. One big trap .A great leveller of sort. _________________ Believe you can and you are halfway there-Theodore Roosevelt Manager Joined: 25 Sep 2015 Posts: 114 Location: United States GMAT 1: 700 Q48 V37 GPA: 3.26 Re: Working at their respective constant rates, machine A makes [#permalink] ### Show Tags 29 Feb 2016, 19:17 banksy wrote: Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 100 copies in 15 minutes. If a number of x machine A and a number of y machine B work simultaneously at their respective rates for 2 hours, what is the total number of copies that they will produce? (1) x = y. (2) 5x + 4y = 90. X*2*(100/12) + Y*2*(100/15) - No.of copies. Multiply by 60. 200*(5X+4Y)=No. of copies. B Sufficient. Manager Joined: 20 Feb 2017 Posts: 166 Location: India Concentration: Operations, Strategy WE: Engineering (Other) Re: Working at their respective constant rates, machine A makes [#permalink] ### Show Tags 08 Jul 2018, 19:39 A : 100 copies in 12 minute or 500 copies in 1hr B: 100 copies in 15 minute or 400 copies in 1hr The question basically asks 500*2*x+400*2*y = ? or the value of 1000x+800y Statement 1 X=Y Clearly not sufficient. Statement 2: 5x + 4y = 90. multiply 200 on both sides 5x*200+4y*200=90*200 =>1000x+800y=18000 Hence sufficient _________________ If you feel the post helped you then do send me the kudos (damn theya re more valuable than$)

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Joined: 14 Dec 2017
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Re: Working at their respective constant rates, machine A makes  [#permalink]

### Show Tags

09 Jul 2018, 08:12
banksy wrote:
Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 100 copies in 15 minutes. If a number of x machine A and a number of y machine B work simultaneously at their respective rates for 2 hours, what is the total number of copies that they will produce?

(1) x = y.
(2) 5x + 4y = 90.

Rate of M/c A = 100 copies/12 min = 100*60/12 = 500 copies/hr

Rate of M/c B = 100 copies/15 min = 100*60/15 = 400 copies/hr

Hence in 2 hrs, one M/c A can make 1000 copies, So x M/c's will make 1000x copies

Similarly, in 2 hrs, one M/c B can make 800 copies, So y M/c's will make 800y copies

Total # of copies = 1000x + 800y

Statement 1: x = y

Total # of copies = 1000x + 800x = 1800x

Statement 1 is not Sufficient.

Statement 2: 5x + 4y = 90

Multiplying both Sides by 200

we get, 1000x + 800y = 1800

Statement 2 is Sufficient.

Thanks,
GyM
_________________
Re: Working at their respective constant rates, machine A makes &nbs [#permalink] 09 Jul 2018, 08:12
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