broall
If n is an integer, is \(\frac{(100-n)}{n}\) an integer?
(1) \(n > 4\)
(2) \(n^2 = 25\)
Target question: Is \(\frac{(100-n)}{n}\) an integer?This is a good candidate for
rephrasing the target question.
The GMAT loves to test the following property:
\(\frac{a-b}{c}=\frac{a}{c}-\frac{b}{c}\)So, \(\frac{100-n}{n}=\frac{100}{n}-\frac{n}{n}=\frac{100}{n}-1\)
Since \(1\) is already an integer, all we need is for \(\frac{100}{n}\) to be an integer.
In order for \(\frac{100}{n}\) to be an integer, we need \(n\) to be a divisor of \(100\)
We can now rephrase the target question as follows:
REPHRASED target question: Is n a divisor of 100? Statement 1: \(n > 4\) There are several values of n that satisfy statement 1. Here are two:
Case a: n = 5. In this case, the answer to the REPHRASED target question is
YES, n is a divisor of 100Case b: n = 6. In this case, the answer to the REPHRASED target question is
NO, n is not a divisor of 100Since we can’t answer the
REPHRASED target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: \(n^2 = 25\) This means that EITHER n = 5 OR n = -5
Since both possible n-values yield the
same answer to the REPHRASED target question (
YES, n is a divisor of 100), statement 2 is SUFFICIENT
Answer: B
Cheers,
Brent
VIDEO ON REPHRASING THE TARGET QUESTION: