Target question: Is (2+x)/(3+y) greater than (2+y)/(3+x) ?Param800 wrote:Can someone show me a short cut method to solve the below question ?
Q. If x and y are positive integers, is (2+x)/(3+y) greater than (2+y)/(3+x) ?
(1) x+y =3
(2) x>y
OA B
Thank You
In other words, is (2+x)/(3+y) > (2+y)/(3+x)?
If x and y are both positive, then the denominators on both sides of the inequality are positive. This means we can simplify the target question by multiplying both sides by (3+y)(3+x) to get:
Is (2+x)(3+x) > (2+y)(3+y)?
To further simplify the target question, we'll first expand both sides to get:
Is 6 + 5x + x^2 > 6 + 5y + y^2
Simplify to get: Is 5x + x^2 > 5y + y^2
Notice that this inequality will true if x > y
Rephrased target question: Is x > y ?
Statement 1: x+y =3
There are several pairs of values that meet this condition. Here are two:
Case a: x=2 and y=1, in which case x is greater than y
Case b: x=1 and y=2, in which case x is not greater than y
Since we cannot answer the rephrased target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: x>y
This definitely helps us answer our rephrased target question with certainty.
So, statement 2 is SUFFICIENT
Answer = B
Cheers,
Brent
