Is y - x positive?
(1) y > 0
(2) x = 1 - y
after rephrasing : is K= y-x>0
st 1 : y>0
Gives no idea abt X. So insufficient
st 2 :
x= 1-y
applying this in the stem; y -(1-y)
------ : y-1+y
= 2y -1
Depending up on the value of y, the output will change. Fro example say Y = 1/2, then K =0
or itcan be like , Y = 2 , then K = 3 which is greater than 0.
Inconsistent . So Insufficient
After combining, y>0 and X= 1-y we will NOT arrive to solid conclusion
when y = 1/4 ( remember Y is >0)
K = 2y-1
= 2 * 1/4 -1
-1/2 which is less than 0
when Y = 4
K = 2*4 -1
=7 >0
Inconsistent as we see K is less than/equalto/greater than zero even after using 2 sts..
So pick E
XY
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
-
gmatmachoman
- Legendary Member
- Posts: 2326
- Joined: Mon Jul 28, 2008 3:54 am
- Thanked: 173 times
- Followed by:2 members
- GMAT Score:710
-
Stuart@KaplanGMAT
- GMAT Instructor
- Posts: 3225
- Joined: Tue Jan 08, 2008 2:40 pm
- Location: Toronto
- Thanked: 1710 times
- Followed by:614 members
- GMAT Score:800
Let's rephrase the question a bit differently:rkhicha wrote:Is y - x positive?
(1) y > 0
(2) x = 1 - y
Have doubts on the answer provided by the book.[/spoiler]
Is y - x > 0?
Is y > x?
(1) as noted, no info about y... insufficient, eliminate A and D.
(2) x = 1 - y
plugging into the question:
Is y > 1 - y?
Is 2y > 1?
Is y > 1/2?
No clue! Insufficient, eliminate B.
Together:
(1) y > 0.
From 2, our question is now: Is y > 1/2?
Maybe yes, maybe no. We could pick y = 100 to get a "yes" answer or y = 1/4 to get a "no" answer.
Not enough information: choose (E).
Stuart Kovinsky | Kaplan GMAT Faculty | Toronto
Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course