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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 ## What is the value of prime number z? tagged by: Gmat_mission ##### This topic has 2 expert replies and 1 member reply ## What is the value of prime number z? ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult What is the value of prime number z? (1) z^3 < 25 (2) z^2 > 1 OA=A. Shouldn't be C the correct answer? I am confused. Please, someone help me. Legendary Member Joined 07 Sep 2017 Posted: 808 messages Followed by: 3 members Upvotes: 6 Hello Gmat_mission. First of all, we know that z is a prime number. First Statement Quote: (1) z^3 < 25 We have the following: - If z=2 then z^3 = 8 < 25. - If z=3, then z^3 = 27 > 25. Therefore, the answer is z=2. So, this statement is sufficient. Second Statement Quote: (2) z^2 > 1 In this case, we have that any prime number z will satisfy that z^2 > 1. So, this statement is not sufficient. Therefore, the correct answer is the option A. I hope it helps you. ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15105 messages Followed by: 1859 members Upvotes: 13060 GMAT Score: 790 Gmat_mission wrote: What is the value of prime number z? (1) z^3 < 25 (2) z^2 > 1 Statement 1: z³ < 25 Only one value for z is possible: z = 2, with the result that z³ = 2³ = 8. If z is any other prime number, the value of z³ will exceed 25. Thus, z=2. SUFFICIENT. Statement 2: z² > 1 Here, z can be ANY PRIME NUMBER, since the square of any prime number will be greater than 1. Since the value of z cannot be determined, INSUFFICIENT. The correct answer is A. _________________ 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. ### GMAT/MBA Expert GMAT Instructor Joined 09 Apr 2015 Posted: 1461 messages Followed by: 17 members Upvotes: 39 Gmat_mission wrote: What is the value of prime number z? (1) z^3 < 25 (2) z^2 > 1 Solution: We are given that z is a prime number and we need to determine its value. Statement One Alone: z^3 < 25 Since the only prime whose cube is less than 25 is 2, then z must be 2 (notice that if z ≥ 3, then z^3 ≥ 27). Statement one alone is sufficient. Statement Two Alone: z^2 > 1 Since any prime number raised to the second power is greater than 1, z could be any prime number. Statement two alone is not sufficient. Answer: A _________________ Jeffrey Miller Head of GMAT Instruction • 1 Hour Free BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • 5-Day Free Trial 5-day free, full-access trial TTP Quant Available with Beat the GMAT members only code • FREE GMAT Exam Know how you'd score today for$0

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