Hi All,

This question can be solved by TESTing VALUES, but you have to really be thorough with your TESTs (and think about what X COULD be given the information in the Facts).

We're asked if Root(7X) is an integer. This is a YES/NO question.

Fact 1: Root(X/7) is an integer.

This Fact tells us that X has to be a specific type of multiple of 7....

IF....

X = 7

the Root(7/7) = 1 and is an integer

Root(49) = 7 and the answer to the question is YES

IF....

X = 28

the Root(28/7) = 2 and is an integer

Root(196) = 14 and the answer to the question is YES

This hints at the pattern that X will be a "perfect square times a multiple of 7', which means that the answer to the question is ALWAYS YES. You can also use prime-factorization to prove that this is the case.

Fact 1 is SUFFICIENT

Fact 2: Root(28X) is an integer.

This Fact tells us that X has to be a specific type of multiple of 7....

IF....

X = 7

the Root(196) = 14 and is an integer

Root(49) = 7 and the answer to the question is YES

IF....

X = 1/28

the Root(1) = 1 and is an integer

Root(7/28) = 1/2 and the answer to the question is NO

Fact 2 is INSUFFICIENT

Final Answer:

GMAT assassins aren't born, they're made,

Rich

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Rich Cohen

Rich.C@empowergmat.com

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