If y > 0, then x is what percent of y?

(1) y = 5x --> x = y*1/5 = y *20/100, so y is 20% of x. Sufficient.

(2) x = 5. Nothing about y. Not sufficient.

Answer: A.
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the question is asking for the ratio of x and y..
1) statement one gives us the relation between x and y in terms of ratio... sufficient..
2) statement just gives us value of x, nothing about y... insufficient
ans A

Hi pinkcupcake,

As Bunuel and chetan2u have pointed out, this question is essentially just about ratios. If you haven't mastered that concept yet, then that's okay, but you will be tested on it repeatedly on the Official GMAT, so the concept is worth some extra practice.

If you don't immediately see the ratio "pattern" in this question, then you can still get to the correct answer by TESTing VALUES and proving that a pattern exists.

We're told that Y is positive. We're asked about how X and Y relate to one another - specifically 'X is what percent of Y?'

Fact 1: Y = 5X

IF....
X = 1
Y = 5
1 is 1/5 of 5; 1/5 = 20%

IF....
X = 2
Y = 10
2 is 2/10 of 10; 2/10 = 20%

IF....
X = 2.5
Y = 12.5
2.5 is 2.5/12.5 of 12.5; 2.5/12.5 = 1/5 = 20%
Etc.

There's clearly a pattern here; X is 20% of Y.
Fact 1 is SUFFICIENT

Fact 2: X = 5

This tells us nothing about Y, so we cannot answer the question.
Fact 2 is INSUFFICIENT.

Final Answer:

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