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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## If the number of cars in city X this year is 520,800... tagged by: Vincen ##### This topic has 6 expert replies and 1 member reply ### Top Member ## If the number of cars in city X this year is 520,800... If the number of cars in city X this year is 520,800 which is 24% more than there were in city X last year, how many cars were there in city X last year? A. 395,808 B. 420,000 C. 447,888 D. 496,800 E. 645,795 The OA is B. How can I solve this PS question? Should I try number by number until I get the correct answer? ### GMAT/MBA Expert GMAT Instructor Joined 22 Aug 2016 Posted: 2004 messages Followed by: 31 members Upvotes: 470 Vincen wrote: If the number of cars in city X this year is 520,800 which is 24% more than there were in city X last year, how many cars were there in city X last year? A. 395,808 B. 420,000 C. 447,888 D. 496,800 E. 645,795 The OA is B. How can I solve this PS question? Should I try number by number until I get the correct answer? What is the source of the question? The GMAT does not expect you to do calculation having ugly numbers. Anyway, here is a way. Say the number of cars in city X last year = 100, thus, the number of cars in city X this year = 100 + 24 = 124 Thus, the actual number of cars in city X last year = 520800*(100/124) = 520800*(25/31). Division of 520800 by the prime number 31 is cumbersome, so let's think of another tactic. 520800*(100/124) > 520800*(100/125) 520800*(100/125) = 520800*(4/5) = 104160*4 = 416640 Thus, the correct answer is greater than 416640. But there are at least two options, B and C, to recon. There is a way to eliminate one of the two options. 520800*(100/124) < 520800*(100/120) 520800*(100/120) = 520800*(5/6) = 86800*5 = 434000. Thus, the correct answer must be less than 434000. The only option that satisfies is option B = 420000. The correct answer: B Hope this helps! -Jay Download free ebook: Manhattan Review GMAT Quantitative Question Bank Guide _________________ Manhattan Review GMAT Prep Locations: New York | Vienna | Kuala Lumpur | Sydney | and many more... Schedule your free consultation with an experienced GMAT Prep Advisor! Click here. ### GMAT/MBA Expert Elite Legendary Member Joined 23 Jun 2013 Posted: 10197 messages Followed by: 497 members Upvotes: 2867 GMAT Score: 800 Hi Vincen, We're told that the number of cars in city X this year is 520,800 and that total is 24% more than there were in city X last year. We're asked for the number of cars that were there in city X last year. While the numbers in this prompt are not 'pretty', the answer choices are 'spaced out' enough that we can do a bit of estimation and some 'brute force' math to get to the answer. To start, 24% of 100,000 = 24,000 (so a 24% increase would be 124,000 total cars). Thus, we can quickly map out increases of 100,000 cars... 200,000 + 48,000 = 248,000 300,000 + 72,000 = 372, 000 400,000 + 96,000 = 496,000 500,000 + 120,000 = 620,000 Since 520,800 is far closer to 496,000 than it is to 620,000, the total number of cars last year would be a bit more than 400,000. There's only one answer that matches... Final Answer: B GMAT assassins aren't born, they're made, Rich _________________ Contact Rich at Rich.C@empowergmat.com ### GMAT/MBA Expert GMAT Instructor Joined 25 Apr 2015 Posted: 2950 messages Followed by: 19 members Upvotes: 43 Vincen wrote: If the number of cars in city X this year is 520,800 which is 24% more than there were in city X last year, how many cars were there in city X last year? A. 395,808 B. 420,000 C. 447,888 D. 496,800 E. 645,795 We are given that the number of cars in city X this year is 520,800, which is 24% more than there were in city X last year. If we let the number of cars in city X last year = c, we can create the following equation: 520,800 = 1.24c c = 420,000 Answer: B _________________ Scott Woodbury-Stewart Founder and CEO scott@targettestprep.com See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews ### GMAT/MBA Expert GMAT Instructor Joined 04 Oct 2017 Posted: 551 messages Followed by: 11 members Upvotes: 180 Quote: If the number of cars in city X this year is 520,800 which is 24% more than there were in city X last year, how many cars were there in city X last year? A. 395,808 B. 420,000 C. 447,888 D. 496,800 E. 645,795 Hi Vincen, Let's take a look at your question. Let the number of cards in city X last year be 'N', then the number of cars in city X is 24% more than x. This can be represented as: $$N+\ \left(24\%\right)N=520,800$$ $$N+\ \left(\frac{24}{100}\right)N=520,800$$ $$N+\ 0.24N=520,800$$ $$1.24N=520,800$$ $$N=\frac{520,800}{1.24}$$ $$N=\frac{520,800\times100}{124}$$ $$N=\frac{130,200\times100}{31}$$ $$N=4,200\times100$$ $$N=420,000$$ Therefore, the number of cars in city X last year was 420,000. Hence, Option B is correct. Hope this helps. I am available if you'd like any follow up. _________________ GMAT Prep From The Economist We offer 70+ point score improvement money back guarantee. Our average student improves 98 points. Free 7-Day Test Prep with Economist GMAT Tutor - Receive free access to the top-rated GMAT prep course including a 1-on-1 strategy session, 2 full-length tests, and 5 ask-a-tutor messages. Get started now. ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15380 messages Followed by: 1872 members Upvotes: 13060 GMAT Score: 790 Vincen wrote: If the number of cars in city X this year is 520,800 which is 24% more than there were in city X last year, how many cars were there in city X last year? A. 395,808 B. 420,000 C. 447,888 D. 496,800 E. 645,795 We can PLUG IN THE ANSWERS, which represent the number of cars last year. Since 24% â‰ˆ 25% = 1/4, adding 1/4 to the correct answer must yield a value close to 520,800. The answer choices range from about 400,000 to about 650,000. Increasing 400,000 by 1/4 -- in other words, increasing 400,000 by 100,000 -- yields 500,000. Too small. Thus, the correct answer must be a bit MORE than 400,000. Eliminate A, D and E. Answer choice B: 420,000 420,000 + (1/4)(420,000) = 420,000 + 105,000 = 525,000. Since increasing 420,000 by 1/4 yields a value a bit more than 520,800, the correct answer cannot be greater than 420,000. Eliminate C. The correct answer is B. _________________ Mitch Hunt Private Tutor for the GMAT and GRE GMATGuruNY@gmail.com If you find one of my posts helpful, please take a moment to click on the "UPVOTE" icon. Available for tutoring in NYC and long-distance. For more information, please email me at GMATGuruNY@gmail.com. Student Review #1 Student Review #2 Student Review #3 Free GMAT Practice Test How can you improve your test score if you don't know your baseline score? Take a free online practice exam. Get started on achieving your dream score today! Sign up now. Master | Next Rank: 500 Posts Joined 29 Nov 2017 Posted: 100 messages Upvotes: 14 Vincen wrote: If the number of cars in city X this year is 520,800 which is 24% more than there were in city X last year, how many cars were there in city X last year? A. 395,808 B. 420,000 C. 447,888 D. 496,800 E. 645,795 The OA is B. How can I solve this PS question? Should I try number by number until I get the correct answer? for 100000 with 24% increase it becomes 124000 for 400000..............................496000 hence figure should be more than 400000 25000 with 24% increase becomes (1/4)*124000=31000 therefore for 425000 with 24% increase it becomes 496000+31000=527000 hence initial figure should be less than 425000 Hence B is correct answer ### GMAT/MBA Expert GMAT Instructor Joined 09 Apr 2015 Posted: 1465 messages Followed by: 19 members Upvotes: 39 Vincen wrote: If the number of cars in city X this year is 520,800 which is 24% more than there were in city X last year, how many cars were there in city X last year? A. 395,808 B. 420,000 C. 447,888 D. 496,800 E. 645,795 We are given that the number of cars in city X this year is 520,800, which is 24% more than there were in city X last year. If we let the number of cars in city X last year = c, we can create the following equation: 520,800 = 1.24c c = 420,000 Answer: B _________________ Jeffrey Miller Head of GMAT Instruction jeff@targettestprep.com See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews • Free Trial & Practice Exam BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • Free Veritas GMAT Class Experience Lesson 1 Live Free Available with Beat the GMAT members only code • Magoosh Study with Magoosh GMAT prep Available with Beat the GMAT members only code • Free Practice Test & Review How would you score if you took the GMAT Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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