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fitzpratik
Posts: 224
09 Jan 2019, 07:19
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D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
55%
(hard)
Question Stats:
49% (01:02) correct
51%
(00:58)
wrong
based on 113
sessions
History
Date
Time
Result
Not Attempted Yet
What is the Greatest Common Factor of Three positive, nonzero numbers X, Y, Z?
A. X= 64, Y = 81
B. Y = 81, Z= 49
A. X= 64, Y = 81
B. Y = 81, Z= 49
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
09 Jan 2019, 07:56
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fitzpratik
Target question: What is the Greatest Common Factor of Three positive, nonzero numbers X, Y, Z?
Statement 1: X= 64, Y = 81
Since the greatest common factor (GCF) of 64 and 81 is 1, the GCF of X, Y, and Z cannot be greater than 1.
Since 1 is a factor of all positive integers, the answer to the target question is the GFC of X, Y and Z is 1
Since we can answer the target question with certainty, statement 1 is SUFFICIENT
Statement 2: Y = 81, Z= 49
We can apply the same logic we applied to statement 1.
Since the greatest common factor (GCF) of 81 and 49 is 1, the GCF of X, Y, and Z cannot be greater than 1.
So, the answer to the target question is the GFC of X, Y and Z is 1
Since we can answer the target question with certainty, statement 2 is SUFFICIENT
Answer: D
Cheers,
Brent
09 Jan 2019, 11:08
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fitzpratik
Great problem! I actually got it wrong at first. A mistake is to think of this problem as a LCM problem (which many problems I have been working lately ask)
(1) Notice that X and Y have a GCF of 1. Since No other number will divide into both X and y, Z can equal 1,2,3,4,5,6,7,8......100 ANYTHING and the GCF will still be 1
Suff
(2) As with (1), notice that only the number 1 will divide into both 81 and 49, therefore it doesnt matte what X is here, the GCF will be 1
Suff
Answer is D
