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Bunuel
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What is the highest common factor of three positive integers x, y, and 03 Mar 2020, 02:39
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Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

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45% (medium)

Question Stats:

54% (01:05) correct 46% (00:57) wrong based on 224 sessions

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What is the highest common factor of three positive integers x, y, and z?

(1) x = 12 and y = 91
(2) y = 91 and z = 90



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D
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GMATinsight
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Schools: IIM (A) ISB '24
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What is the highest common factor of three positive integers x, y, and 03 Mar 2020, 03:26
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Bunuel
What is the highest common factor of three positive integers x, y, and z?

(1) x = 12 and y = 91
(2) y = 91 and z = 90


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Question: GCD of x, y and z = ?

Statement 1: x = 12 and y = 91

GCD of x and y = 1

i.e. GCD of x, y and z will also be 1 irrespective of value of z hence

SUFFICIENT

Statement 2: z = 90 and y = 91

GCD of z and y = 1

i.e. GCD of x, y and z will also be 1 irrespective of value of x hence

SUFFICIENT

Answer: Option D
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What is the highest common factor of three positive integers x, y, and 26 May 2024, 13:02
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IMO option a gives us the value for x and y, and option b gives us to y and z. To calculate HCF we need both options.
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What is the highest common factor of three positive integers x, y, and 26 May 2024, 13:08
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Invincible_147
What is the highest common factor of three positive integers x, y, and z?

(1) x = 12 and y = 91
(2) y = 91 and z = 90

IMO option a gives us the value for x and y, and option b gives us to y and z. To calculate HCF we need both options.
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­
It seems that you've missed the solution provided above. For each statement, the numbers given are co-prime, meaning that they do not share any common factor except 1. Hence, irrespective of the third number, the highest common factor for all three would still be 1.

P.S. Worth noting though that such type of pure algebraic questions are no longer a part of the DS syllabus of the GMAT.­

­DS questions in GMAT Focus encompass various types of word problems, such as:
  • Word Problems
  • Work Problems
  • Distance Problems
  • Mixture Problems
  • Percent and Interest Problems
  • Overlapping Sets Problems
  • Statistics Problems
  • Combination and Probability Problems

While these questions may involve or necessitate knowledge of algebra, arithmetic, inequalities, etc., they will always be presented in the form of word problems. You won't encounter pure "algebra" questions like, "Is x > y?" or "A positive integer n has two prime factors..."­

­Check GMAT Syllabus for Focus Edition­

Hope it helps.­
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