piyushkush wrote:IS 1/(x-y) < y - x ?
S1) y is positive.
S2) x is negative.
Target question: Is 1/(x-y) < y - x ?
Statement 1: y is positive.
This statement does not
FEEL sufficient to answer the target question (because we're only given information about 1 of the 2 variables), so I'm going to
TEST some values.
There are several values of x and y that satisfy statement 1. Here are two:
Case a: x = 1 and y = 2, in which case
1/(x-y) is LESS THAN y - x
Case b: x = 2 and y = 1, in which case
1/(x-y) is GREATER THAN y - x
Since 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: https://www.gmatprepnow.com/articles/dat ... lug-values
Statement 2: x is negative
This statement does not FEEL sufficient either, so I'm going to TEST some values.
There are several values of x and y that satisfy statement 2. Here are two:
Case a: x = -1 and y = 0, in which case
1/(x-y) is LESS THAN y - x
Case b: x = -1 and y = -2, in which case
1/(x-y) is GREATER THAN y - x
Since we cannot answer the
target question with certainty, statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined
If y is positive AND x is negative, then 1/(x-y) is NEGATIVE, and y-x is POSITIVE
So, we can be
certain that
1/(x-y) is LESS THAN y - x
Since we can answer the
target question with certainty, the combined statements are SUFFICIENT
Answer =
C
Cheers,
Brent
