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10 Oct 2017, 01:16
Kudos
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B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
95%
(hard)
Question Stats:
32% (02:12) correct
68%
(02:18)
wrong
based on 81
sessions
History
Date
Time
Result
Not Attempted Yet
If r and s are nonzero integers, is r/s an integer ?
(1) s – 4 = (r + 2)(r – 2)
(2) r^2 – s^2 = -12
(1) s – 4 = (r + 2)(r – 2)
(2) r^2 – s^2 = -12
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
10 Oct 2017, 01:52
Kudos
Bookmarks
If r and s are nonzero integers, is r/s an integer ?
(1) s – 4 = (r + 2)(r – 2)
=> \(s-4=r^2-4\)
=> \(s=r^2\)
if r =1 s=1 => \(\frac{r}{s}\) integer True
if r = 2 s = 4 => \(\frac{r}{s}\) not an integer
=> For \(r\neq{1}\) => \(s>r\) and \(\frac{r}{s}\) is not an integer
Insufficient
(2) \(r^2 – s^2 = -12\)
=> \(s^2 – r^2 = 12\)
=> That is r and s are not equal and |s| > |r|
=> \(\frac{r}{s}\) cannot be an integer
Sufficient
Answer: B
(1) s – 4 = (r + 2)(r – 2)
=> \(s-4=r^2-4\)
=> \(s=r^2\)
if r =1 s=1 => \(\frac{r}{s}\) integer True
if r = 2 s = 4 => \(\frac{r}{s}\) not an integer
=> For \(r\neq{1}\) => \(s>r\) and \(\frac{r}{s}\) is not an integer
Insufficient
(2) \(r^2 – s^2 = -12\)
=> \(s^2 – r^2 = 12\)
=> That is r and s are not equal and |s| > |r|
=> \(\frac{r}{s}\) cannot be an integer
Sufficient
Answer: B
10 Oct 2017, 02:14
Kudos
Bookmarks
We need to discover whether s is a factor of r
(1)s-4=(r-2)(r+2)
s-4=r^2-4
s=r^2
s=1; r=1 => r/s=1 YES-integer
s=4; r=2 r/s= 2/4=1/2 NO
Insufficient
(2) r^2-s^2= -12
This statement tells us that |r|<|s| hence r/s would not be an integer Sufficient.
Answer B.
(1)s-4=(r-2)(r+2)
s-4=r^2-4
s=r^2
s=1; r=1 => r/s=1 YES-integer
s=4; r=2 r/s= 2/4=1/2 NO
Insufficient
(2) r^2-s^2= -12
This statement tells us that |r|<|s| hence r/s would not be an integer Sufficient.
Answer B.
