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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 average of 25 values is equal to product. . . tagged by: Brent@GMATPrepNow ##### This topic has 4 expert replies and 0 member replies ### Top Member ## The average of 25 values is equal to product. . . The average of 25 values is equal to product of these values. If only one of the numbers is 0, at most how many numbers can be greater than zero? A) 0 B) 12 C) 13 D) 23 E) 24 The OA is D. According to the hypothesis, the average is 0. But, how can I calculate how many of the numbers are positives? ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 13038 messages Followed by: 1251 members Upvotes: 5254 GMAT Score: 770 Vincen wrote: The average of 25 values is equal to product of these values. If only one of the numbers is 0, at most how many numbers can be greater than zero? A) 0 B) 12 C) 13 D) 23 E) 24 If one of the 25 values is zero, then the PRODUCT of the 25 values will be 0 So, the AVERAGE of the 25 values is also 0 If the average is 0, then the SUM of all 25 values must be 0 At most how many numbers can be greater than zero? We already know that one value is 0. Can the other 24 values be greater than 0? No. The sum of 0 and 24 positive values will always be positive. So, we can ELIMINATE answer choice E Can 23 values be greater than 0? Yes. How about: {-23, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 } Here, the average = 0, and we have 23 positive values in the set. Answer: D Cheers, Brent _________________ Brent Hanneson â€“ Creator of GMATPrepNow.com Use my video course along with Sign up for free Question of the Day emails And check out all of these 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! ### GMAT/MBA Expert Elite Legendary Member Joined 23 Jun 2013 Posted: 10197 messages Followed by: 497 members Upvotes: 2867 GMAT Score: 800 Hi Vincen, This is a great 'concept' question - meaning that if you understand the concepts involved, then you don't have to do much math to get to the correct answer. We're told that there are 25 numbers and that the AVERAGE of the numbers = PRODUCT of the numbers. THAT type of relationship can clearly only happen under certain circumstances. We're also told that JUST ONE of the numbers is 0. We're asked for the maximum number of those 25 values could be GREATER than 0. Since we have a 0 in the group, we know that the product will be 0 (since anything multiplied by 0 will equal 0). To get an AVERAGE of 0, the SUM of all 25 terms must 'cancel out' and leave us with a 0. There are no limit on what the values could be, so as long as we had one NEGATIVE value to 'offset' the sum of all of the positive values, then we could hit a total sum of 0. Thus, we could have.... 1 negative 1 zero 23 positives Final Answer: D GMAT assassins aren't born, they're made, Rich _________________ Contact Rich at Rich.C@empowergmat.com ### GMAT/MBA Expert GMAT Instructor Joined 09 Apr 2015 Posted: 1465 messages Followed by: 19 members Upvotes: 39 Vincen wrote: The average of 25 values is equal to product of these values. If only one of the numbers is 0, at most how many numbers can be greater than zero? A) 0 B) 12 C) 13 D) 23 E) 24 Since the average is equal to the product and one value is zero, the product is zero. Thus, in order to have an average of zero, we need the sum to be zero also. We can have 23 numbers that are positive, one that is zero, and one that is negative with its absolute value as the sum of the 23 positive numbers. Answer: D _________________ 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 ### GMAT/MBA Expert GMAT Instructor Joined 04 Oct 2017 Posted: 551 messages Followed by: 11 members Upvotes: 180 Quote: The average of 25 values is equal to product of these values. If only one of the numbers is 0, at most how many numbers can be greater than zero? A) 0 B) 12 C) 13 D) 23 E) 24 Hi Vincen, Let's take a look at your question. Out of 25 values, one is 0. Hence, Product of all 25 values = 0 Since average and product of these 25 values are equal. Therefore, Average of 25 values = 0 For average to be equal to zero, the sum of 25 values should be equal to zero. Sum can be zero if, One value = 0 23 values = positive One value = negative, that should be equal to the sum of 23 positive values. Hence, Option D is correct. Hope it 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. • Free Veritas GMAT Class Experience Lesson 1 Live Free Available with Beat the GMAT members only code • Free Trial & Practice Exam BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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