BTGModeratorVI wrote: ↑Thu Jun 11, 2020 8:42 am
Is a + b > c + d ?
(1) a > c
(2) d < b
Answer:
C
Source: Manhattan prep
Target question: Is a + b > c + d ?
Statement 1: a > c
Since we have no information about b or d, we cannot determine whether
a + b > c + d
Since we cannot answer the
target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: d < b
Since we have no information about a or c, we cannot determine whether
a + b > c + d
Since we cannot answer the
target question with certainty, statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined
Statement 1 tells us that
a > c
Statement 2 tells us that
b > d (NOTE: I rewrote the inequality so that the inequality symbol is facing the other direction)
Since the two inequality symbols are facing in the SAME DIRECTION, we can ADD THEM to get:
a + b > c + d
PERFECT.
We can now say, with certainty that the answer to the target question is
YES, a + b IS greater than c + d
Since we can answer the
target question with certainty, the combined statements are SUFFICIENT
Answer: C
