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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 The sequence a(1), a(2), a(3), ... a(n) of n integers is suc This topic has 1 expert reply and 0 member replies Top Member The sequence a(1), a(2), a(3), ... a(n) of n integers is suc Timer 00:00 Your Answer A B C D E Global Stats Difficult The sequence a(1), a(2), a(3), ... a(n) of n integers is such that a(k) = k if k is odd, and a(k) = -a(k-1) if k is even. Is the sum of the terms in the sequence positive? (1) n is odd (2) a(n) is positive OA D Source: GMAT Prep GMAT/MBA Expert GMAT Instructor Joined 22 Aug 2016 Posted: 1975 messages Followed by: 30 members Upvotes: 470 BTGmoderatorDC wrote: The sequence a(1), a(2), a(3), ... a(n) of n integers is such that a(k) = k if k is odd, and a(k) = -a(k-1) if k is even. Is the sum of the terms in the sequence positive? (1) n is odd (2) a(n) is positive OA D Source: GMAT Prep From the given information, we have a(1) = 1; a(2) = -a(1) = -1; a(3) = 3; a(4) = -a(3) = -3; a(5) = 5; a(6) = -a(5) = -5 ... We see that if the number terms is even, the sum of the terms = 0. Take for example, the sum of 1 + (-1) + 3 + (-3) = 0. However, if the number terms is odd, the sum of the terms = positive. Take for example, the sum of 1 + (-1) + 3 + (-3) + 5 = 5. So, if are able to ascertain whether n is even or odd, we get the answer. Let's take each statement one by one. (1) n is odd. Sufficient. The answer is Yes. (2) a(n) is positive. Since any term is positive when the term is odd, thus n is odd. Sufficient. The answer is Yes. The correct answer: D Hope this helps! -Jay _________________ Manhattan Review GMAT Prep Locations: Manhattan Review New Delhi | Hyderabad | GRE Prep Chennai | Madhapur GRE Coaching | and many more... Schedule your free consultation with an experienced GMAT Prep Advisor! Click here. • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE 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 • 1 Hour Free BEAT THE GMAT EXCLUSIVE 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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