BTGModeratorVI wrote: ↑Tue May 12, 2020 2:13 pm
For integers a, b, and c, a/(b-c) = 1. What is the value of (b-c)/b?
(1) a/b = 3/5
(2) a and b have no common factors greater than 1
Answer:
A
Source: Official guide
Given: a/(b - c) = 1
Target question: What is the value of (b-c)/b ?
This is a good candidate for
rephrasing the target question.
Aside: The video below has tips on rephrasing the target question
If
a/(b - c) = 1, then we know that a = b - c
The target question asks "
What is the value of (b-c)/b ?"
Since a = b - c, we can replace b - c with a to get:
REPHRASED target question: What is the value of a/b ?
Statement 1: a/b = 3/5
Perfect!
The answer to the REPHRASED target question is
a/b = 3/5
Since we can answer the
REPHRASED target question with certainty, statement 1 is SUFFICIENT
Statement 2: a and b have no common factors greater than 1
There are several values of a and b that satisfy statement 2. Here are two:
Case a: a = 1 and b = 2. In this case, the answer to the REPHRASED target question is
a/b = 1/2
Case b: a = 2 and b = 3. In this case, the answer to the REPHRASED target question is
a/b = 2/3
Since we cannot answer the
REPHRASED target question with certainty, statement 2 is NOT SUFFICIENT
Answer: A
