Bunuel wrote:

Is xy > 3 ?

(1) x + y > 3

(2) x – y > 3

Target question: Is xy > 3 ? Statement 1: x + y > 3 This statement doesn't FEEL sufficient, so I'll TEST some values.

There are several values of x and y that satisfy statement 1. Here are two:

Case a: x = 10 and y = 1, in which case xy = (10)(1) = 10. In other words,

xy > 3Case b: x = 4 and y = 0.5, in which case xy = (4)(0.5) = 2. In other words,

xy < 3Since we cannot answer the

target question with certainty, statement 1 is NOT SUFFICIENT

Aside: For more on this idea of plugging in values when a statement doesn't feel sufficient, you can read my article: http://www.gmatprepnow.com/articles/dat ... lug-values Statement 2: x - y > 3 This statement doesn't FEEL sufficient either, so I'll TEST some values.

There are several values of x and y that satisfy statement 2. Here are two:

Case a: x = 10 and y = 1, in which case xy = (10)(1) = 10. In other words,

xy > 3Case b: x = 4 and y = 0.5, in which case xy = (4)(0.5) = 2. In other words,

xy < 3Since we cannot answer the

target question with certainty, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined Since I was able to use the SAME x-values and y-values in the two statements above to show the individual statements were not sufficient, we can conclude that the COMBINED statements are not sufficient.

Answer: E

To clarify, the following cases satisfy the conditions of BOTH statements.

Case a: x = 10 and y = 1, in which case xy = (10)(1) = 10. In other words,

xy > 3Case b: x = 4 and y = 0.5, in which case xy = (4)(0.5) = 2. In other words,

xy < 3Since we cannot answer the

target question with certainty, the statement COMBINED are NOT SUFFICIENT

Cheers,

Brent

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Brent Hanneson – Founder of gmatprepnow.com