Bunuel wrote:
a, b, c, d are positive integers such that exactly one of the following inequalities is false. Which inequality is false?
(A) a<b
(B) c<d
(C) a+c<b+c
(D) a+c<b+d
(E) a<b+c+d
I'm not sure whether we can see such problem on GMAT, but I found this one quite interesting so posting for discussion.
An algebrical approach:
first of all (A) a<b and (C) a+c<b+c are the same: both tell us thata<b .
Since exactly one inequality is false, both A and C must be true. With
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