Bunuel wrote:
Is d ≠ e ?
(1) d > e + 1
(2) d < e + 2
Target question: Is d ≠ e ?This is a good candidate for
rephrasing the target question.
If d = e, then we can say that d - e = 0
Likewise, if d ≠ e then we can say that d - e ≠ 0
REPHRASED target question: Is d - e ≠ 0 ? Statement 1: d > e + 1 Subtract e from both sides to get: d - e > 1
If d - e is GREATER THAN 1, we can be certain that d - e will NEVER EQUAL ZERO.
In other words,
d - e ≠ 0Since we can answer the
REPHRASED target question with certainty, statement 1 is SUFFICIENT
Statement 2: d < e + 2 Subtract e from both sides to get: d - e < 2
If d - e is LESS THAN 2,
it's POSSIBLE that d - e = 0, and it's POSSIBLE that d - e ≠ 0Since we cannot answer the
REPHRASED target question with certainty, statement 2 is NOT SUFFICIENT
Answer: A
ASIDE: If you're not convinced that statement 2 is not sufficient, consider these two cases that yield contradictory answers to the target question:
Case a: d = 3 and e = 2. In this case,
d - e ≠ 0Case b: d = 3 and e = 3. In this case,
d - e = 0RELATED VIDEO FROM OUR COURSE
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