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15 Dec 2016, 01:17
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D
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Difficulty:
25%
(medium)
Question Stats:
77% (00:50) correct
23%
(01:00)
wrong
based on 75
sessions
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If x and y are prime numbers, what is the smallest prime factor of \(xy^3\) ?
1) x=even
2) x+y=odd
1) x=even
2) x+y=odd
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
15 Dec 2016, 04:19
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MathRevolution
1) We know that smallest prime factor is \(2\) which is the only even prime. Sufficient
2) We assume that x and y are different primes. In order for \(x + y\) to be odd, \(x\) and \(y\) should be of different parity, which gives us \(x = 2\) again. Sufficient.
Answer D
18 Dec 2016, 18:18
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==> In the original condition, there are only 2 variables (x, y), hence C is most likely to be the answer. For con 1), if x=even, an even number that is also a prime number is only “2”, so the smallest prime factor of \(xy^3\) becomes 2, and hence it is sufficient.
For con 2), in order to get x+y=odd, since it is even+odd=odd, x or y always becomes “2”, so the smallest prime factor of \(xy^3\) becomes “2”, and hence it is also sufficient.
This question is also related to mistake type 4(B), where con 1) is easy and con 2) is difficult. This type of question is a 5051-level question.
The answer is D.
Answer: D
For con 2), in order to get x+y=odd, since it is even+odd=odd, x or y always becomes “2”, so the smallest prime factor of \(xy^3\) becomes “2”, and hence it is also sufficient.
This question is also related to mistake type 4(B), where con 1) is easy and con 2) is difficult. This type of question is a 5051-level question.
The answer is D.
Answer: D
