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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 ## Which of the following are/is prime? tagged by: M7MBA ##### This topic has 2 expert replies and 2 member replies ## Which of the following are/is prime? Which of the following are/is prime? I. 143 II. 147 III. 149 (A) II only (B) III only (C) I & II (D) I & III (E) I, II, & III The OA is the option B. Experts, what is the faster way to solve this PS question? I know that 147 is not prime. But how can I determine if (I) or (III) are primes? Moderator Joined 30 Aug 2017 Posted: 772 messages Followed by: 6 members Top Reply prime factors are numbers that are only divisible by one and its self. Here, i. 143 =11*13 ii. 147 =7*21 iii. 149=1*149 roman figure iii is an example of prime factors because it has only 2 factors which is 1 and 149. Answer is b ### GMAT/MBA Expert GMAT Instructor Joined 25 Apr 2015 Posted: 1778 messages Followed by: 14 members Upvotes: 43 Top Reply M7MBA wrote: Which of the following are/is prime? I. 143 II. 147 III. 149 (A) II only (B) III only (C) I & II (D) I & III (E) I, II, & III Since 143 = 11 x 13, 143 is not a prime. Since 147 = 7 x 21, 147 is not a prime. 149 is a prime since there is no multiplication of two numbers that equals 149 other than 1 x 149. Answer: B _________________ Scott Woodbury-Stewart Founder and CEO ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 12442 messages Followed by: 1244 members Upvotes: 5254 GMAT Score: 770 M7MBA wrote: Which of the following are/is prime? I. 143 II. 147 III. 149 (A) II only (B) III only (C) I & II (D) I & III (E) I, II, & III I. 143 143 = 11 x 13 So, 143 is NOT prime. ELIMINATE C, D and E II. 147 Check the sum of the digits. 1+4+7 = 12 Since 12 is divisible by 3, we know that 147 is divisible by 3 So, 147 is NOT prime. ELIMINATE A By the process of elimination, the correct answer is B Cheers, Brent _________________ Brent Hanneson â€“ Creator of GMATPrepNow.com Use our video course along with Sign up for our free Question of the Day emails And check out all of our free resources GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMATâ€™s FREE 60-Day Study Guide and reach your target score in 2 months! Legendary Member Joined 07 Sep 2017 Posted: 808 messages Followed by: 3 members Upvotes: 6 This is how I did it. Since 147 is divisible by 3 (because 1+4+7=12 and it is divisible by 3) then I discarded the options (A), (C) and (E). Now, watching the options (B) and (D) I knew that III is prime. Hence, I only had to check the option I = 143. But 143=11*13, thus it is not prime. Therefore, I concluded that B is the correct option. • Free Practice Test & Review How would you score if you took the GMAT Available with Beat the GMAT members only code • Magoosh Study with Magoosh GMAT prep Available with Beat the GMAT members only code • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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