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13 Jan 2014, 01:54
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25% (medium)

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67% (00:55) correct 33% (01:15) wrong based on 742 sessions

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The Official Guide For GMAT® Quantitative Review, 2ND Edition

Last year, if Elena spent a total of $720 on newspapers, magazines, and books, what amount did she spend on newspapers? (1) Last year, the amount that Elena spent on magazines was 80 percent of the amount that she spent on books. (2) Last year, the amount that Elena spent on newspapers was 60 percent of the total amount that she spent on magazines and books. Data Sufficiency Question: 33 Category: Arithmetic Percents Page: 155 Difficulty: 600 GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition - Quantitative Questions Project Each week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution. We'll be glad if you participate in development of this project: 1. Please provide your solutions to the questions; 2. Please vote for the best solutions by pressing Kudos button; 3. Please vote for the questions themselves by pressing Kudos button; 4. Please share your views on difficulty level of the questions, so that we have most precise evaluation. Thank you! _________________ Math Expert Joined: 02 Sep 2009 Posts: 46305 Re: Last year, if Elena spent a total of$720 on newspapers, mag [#permalink]

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13 Jan 2014, 01:55
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SOLUTION:

Last year, if Elena spent a total of $720 on newspapers, magazines, and books, what amount did she spend on newspapers? Given that $$n + m + b = 720$$, find the value of n. (1) Last year, the amount that Elena spent on magazines was 80 percent of the amount that she spent on books --> $$m=0.8b$$ --> $$n + 0.8b + b = 720$$ --> $$n=720-\frac{9}{5}b$$. Not sufficient. (2) Last year, the amount that Elena spent on newspapers was 60 percent of the total amount that she spent on magazines and books --> $$n=0.6(m+b)$$ --> $$\frac{5}{3}n=m+b$$ --> substitute: $$n + m + b =n+\frac{5}{3}n =720$$ --> we can solve for n. Sufficient. Answer: B. _________________ Intern Joined: 10 May 2012 Posts: 2 Re: Last year, if Elena spent a total of$720 on newspapers, mag [#permalink]

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13 Jan 2014, 22:54
1
Last year, if Elena spent a total of $720 on newspapers, magazines, and books, what amount did she spend on newspapers? (1) Last year, the amount that Elena spent on magazines was 80 percent of the amount that she spent on books. (2) Last year, the amount that Elena spent on newspapers was 60 percent of the total amount that she spent on magazines and books. Data Sufficiency Question: 33 Category: Arithmetic Percents Page: 155 Difficulty: 600 My Solution: From Question: N(newspapers) + M (magazines) + B(books) = 720 From (1) : M =80/100(B) M= 4/5B Subs in Question: N+ 4/5B+B = 720 ( Two unknown values), So insufficient. From(2): N=60/100(M+B) N=3/5(M+B) Since we need to find N, Keeping N in the equation. So M=5/3N-B Subs in Main equation: N+ 5/3N-B +B= 720 N+5/3N= 720 So, can find N... Sufficient! My ANSWER : B Director Joined: 03 Feb 2013 Posts: 907 Location: India Concentration: Operations, Strategy GMAT 1: 760 Q49 V44 GPA: 3.88 WE: Engineering (Computer Software) Re: Last year, if Elena spent a total of$720 on newspapers, mag [#permalink]

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14 Jan 2014, 11:58
1
Bunuel wrote:
The Official Guide For GMAT® Quantitative Review, 2ND Edition

Last year, if Elena spent a total of $720 on newspapers, magazines, and books, what amount did she spend on newspapers? (1) Last year, the amount that Elena spent on magazines was 80 percent of the amount that she spent on books. (2) Last year, the amount that Elena spent on newspapers was 60 percent of the total amount that she spent on magazines and books. Statement 1) magazine = .8 of books. As newspaper expenditure is not provided. Hence Not sufficient. Statement 2) Lets assume magazine expenditure = m, newspaper expenditure = n and book expenditure = b then n = 0.6(m+b) we know that m+n+b =$720
=> 1.6 (m+b) = $720 We can find out the value of (m+b) and from there we can find the value of n as well. hence Option B) _________________ Thanks, Kinjal My Application Experience : http://gmatclub.com/forum/hardwork-never-gets-unrewarded-for-ever-189267-40.html#p1516961 Linkedin : https://www.linkedin.com/in/kinjal-das/ Please click on Kudos, if you think the post is helpful Manager Joined: 29 Jan 2017 Posts: 51 Re: Last year, if Elena spent a total of$720 on newspapers, mag [#permalink]

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04 Aug 2017, 17:54
In regards to st2, is it the same as saying N = 60 % of 720 and M+B = 40% of 720?
We can't figure out exact values for M and B, but we can for M+B

Just so I have a better understanding for these types of questions

Thanks

kinjiGC wrote:
Bunuel wrote:
The Official Guide For GMAT® Quantitative Review, 2ND Edition

Last year, if Elena spent a total of $720 on newspapers, magazines, and books, what amount did she spend on newspapers? (1) Last year, the amount that Elena spent on magazines was 80 percent of the amount that she spent on books. (2) Last year, the amount that Elena spent on newspapers was 60 percent of the total amount that she spent on magazines and books. Statement 1) magazine = .8 of books. As newspaper expenditure is not provided. Hence Not sufficient. Statement 2) Lets assume magazine expenditure = m, newspaper expenditure = n and book expenditure = b then n = 0.6(m+b) we know that m+n+b =$720
=> 1.6 (m+b) = $720 We can find out the value of (m+b) and from there we can find the value of n as well. hence Option B) Re: Last year, if Elena spent a total of$720 on newspapers, mag   [#permalink] 04 Aug 2017, 17:54
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