BTGModeratorVI wrote: ↑Fri Jul 03, 2020 7:16 am
If a > 2, is b < 1?
(1) ab<2
(2) ab>0
Answer:
A
Source: Economist GMAT
Target question: Is b < 1?
Given: a > 2
Statement 1: ab < 2
Since we're told that a > 2, we know that a is POSITIVE, which means we can safely divide both sides of the inequality by a.
When we do this we get: b < 2/a
Since a > 2, we know that the fraction's denominator is greater its numerator, which means 2/a must be less than 1
So, 2/a < 1
Since b < 2/a, we get: b < 2/a < 1
In other words,
b < 1
Since we can answer the
target question with certainty, statement 1 is SUFFICIENT
Statement 2: ab > 0
Let's TEST some numbers.
There are several values of a and b that satisfy statement 2. Here are two:
Case a: a = 3 and b = 2, in which case
b > 1
Case b: a = 3 and b = 0.1, in which case
b < 1
Since we cannot answer the
target question with certainty, statement 2 is NOT SUFFICIENT
Answer: A
Cheers,
Brent
