If x+y is an integer, is y an integer?
1) x-y is an integer.
2) x+2y is an integer.
The answer is B. but couldn't find my way out of this maze.
Please give me a way~!!
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
integer..
This topic has expert replies
-
sankruth
- Master | Next Rank: 500 Posts
- Posts: 195
- Joined: Sun Oct 21, 2007 4:33 am
- Thanked: 10 times
St 1
x - y is Integer
x = 1.5; y = 0.5
x+y = 2 (Int)
x-y = 1 (Int)
But y not Integer. So St1 INSUFF
St 2
x + 2y = (x + y) + y
(Integer + Non Integer) CANNOT add up to an Integer. Since (x + y) is Integer, s y must be an Integer.
SUFF, Hence B
x - y is Integer
x = 1.5; y = 0.5
x+y = 2 (Int)
x-y = 1 (Int)
But y not Integer. So St1 INSUFF
St 2
x + 2y = (x + y) + y
(Integer + Non Integer) CANNOT add up to an Integer. Since (x + y) is Integer, s y must be an Integer.
SUFF, Hence B
-
preciousrain7
- Senior | Next Rank: 100 Posts
- Posts: 78
- Joined: Thu Dec 06, 2007 4:16 pm
- Location: NYC, NY
- Thanked: 2 times
How do you know that X+Y is an integer?sankruth wrote:St 1
x - y is Integer
x = 1.5; y = 0.5
x+y = 2 (Int)
x-y = 1 (Int)
But y not Integer. So St1 INSUFF
St 2
x + 2y = (x + y) + y
(Integer + Non Integer) CANNOT add up to an Integer. Since (x + y) is Integer, s y must be an Integer.
SUFF, Hence B
Using your equation:
(X+Y)+Y: what if X=1.5 and Y=.5, then the answer will end up being an integer...
-
preciousrain7
- Senior | Next Rank: 100 Posts
- Posts: 78
- Joined: Thu Dec 06, 2007 4:16 pm
- Location: NYC, NY
- Thanked: 2 times
