Problem found in math online lab regarding yes/no DS

[angs316]

Source Online Lab Yes/No DS

If x is a positive integer, is sqrt (x) an integer?
1. sqrt(4x) is an integer
2. sqrt(3x) is not an integer

If we take x= 1/4 you will notice that this satisfies the criteria in the question and no.1 however sqrt(1/4) is not an integer.
Thus answer a is insufficient.

The online lab claims answer choice (A) to be correct. I believe this is wrong. Am i correct?

[mithunsam]

The quesiton specifically states that x is a +ve integer. So, you cannot substitute x=1/4

For statement 1 to be true, x has to be a perfect square (like 1, 4, 9 etc). Therefore, statement 1 is sufficient.

[aalokshah85]

Source Online Lab Yes/No DS

If x is a positive integer, is sqrt (x) an integer?
1. sqrt(4x) is an integer
2. sqrt(3x) is not an integer

If we take x= 1/4 you will notice that this satisfies the criteria in the question and no.1 however sqrt(1/4) is not an integer.
Thus answer a is insufficient.

The online lab claims answer choice (A) to be correct. I believe this is wrong. Am i correct?

The question states that x is a POSITIVE INTEGER

Statement 1: States sqrt (4x) is an integer - this is sufficient 4 - is a perfect square (2*2) in order for root of 4x to be an integer, x must also be a perfect square (the square root of which must be an integer) you can also take examples (such as 9)

Statement 2: States sqrt(3x) is not an integer - Not sufficient - x could be 9 (3*3) or anyother perfect square (in which case DS answer is Yes) thus 3x = 27 or x could be 7 or any other number that is not a perfect Square (in which case DS answer is No)

Ans: (a)

[RonPurewal]

hi -- this is the wrong folder for this question; this folder is for GMAT PREP SOFTWARE PROBLEMS ONLY.

if you wish to post this problem, please post it in the MGMAT CAT or GENERAL MATH folder.
thank you.

this thread is locked and will be deleted in about 1 week; if you wish to continue the discussion, please post a new thread in the correct folder.