4meonly wrote:Is a/b an integer?
(1) 4a/b is an integer
4(a/b) is integer
if it is 4, a/b = integer
if it is 5 , a/b is not an integer
INSUF
(2) 4b/a is an integer
if b/a = 1, 4b/a is an integer and a/b is an integer
if b/a is 2 , 4b/1 is an integer but a/b is not! (1/2)
(1+2)
a = 4 b = 8
4a/b = integer
4b/a = integer
a/b is not an integer
I learned this method from Cramya
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Number properties
Source: Beat The GMAT — Data Sufficiency |
LGTCH
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"DON'T LET ANYONE STEAL YOUR DREAM!"
got it 
aj5105 wrote:I got C as the answer.
Cramya,
could you please explain taking both together?
thanks!
4a/b and 4b/a are integers and a/b is integer if a=6 and b=3
To prove insufficiency
Take a=2 b=4 for stmt I and stmt II a/b not an integer
Together
Again take a=2 b=4 a/b not integer
Take a=6 b=3 a/b integer
Hence E)
To prove insufficiency
Take a=2 b=4 for stmt I and stmt II a/b not an integer
Together
Again take a=2 b=4 a/b not integer
Take a=6 b=3 a/b integer
Hence E)
Is a/b an integer?4meonly wrote:Are there any methods without plugin numbers?
Algebraic?
(1) 4a/b is an integer
a/b=x
4X=K
X=K/4
If K is divisible with 4, X is integer
If not X is not an integer
(2) 4b/a is an integer
4/X=K
X=4/K
If 4 is divisible with K , X is integer if NOT it is not
Together
4/K=K/4
If K is 4 they X is integer
If K is not 4, X is not an integer
LGTCH
---------------------
"DON'T LET ANYONE STEAL YOUR DREAM!"
---------------------
"DON'T LET ANYONE STEAL YOUR DREAM!"
