With data sufficiency question, the ONLY thing that matters is whether or not we can answer the
target question with absolute certainty. The actual answer to the target question doesn't matter. It's all about whether we have sufficient information to be certain about our answer to the
target question.
candygal79 wrote:If y > 0, is x less than 0?
1) xy = 16
2 ) x - y = 6
Target question: Is x less than 0?
REPHRASED target question: Is x negative?
Given: y > 0
In other words, y is POSITIVE
Statement 1: xy = 16
In other words, xy = POSITIVE value
Since we're told that y is POSITIVE, we get: x(POSITIVE) = POSITIVE value
From our rules about the products of positive and negative values, we can conclude, with certainty, that
x is POSITIVE.
Is other words,
x is definitely NOT negative
Since we can answer the
target question with certainty, statement 1 is SUFFICIENT
Statement 2: x - y = 6
We can rewrite this as: x = 6 + y
Since we're told that y is POSITIVE, we can write: x = 6 + (some POSITIVE value)
In other words, x will be greater than 6, which means we can conclude, with certainty, that
x is POSITIVE.
Is other words,
x is definitely NOT negative
Since we can answer the
target question with certainty, statement 2 is SUFFICIENT
Answer =
D
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
