Self-made (inequality)

This topic has expert replies
Source: — Data Sufficiency |

User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Wed Mar 16, 2016 10:38 am
iMyself wrote:is x<y?

(1) y/x<1
(2) y<0
Both statements are satisfied if y=-1 and x=1:
Statement 1: -1/1 < 1
Statement 2: -1 < 0
In this case, x>y.

Both statements are satisfied if y=-1 and x=-2:
Statement 1: -1/-2 < 1
Statement 2: -1 < 0
In this case, x<y.

Since the answer to the question stem is NO in the first case but YES in the second case, the two statements combined are INSUFFICIENT.

The correct answer is E.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3

GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Thu Mar 17, 2016 10:33 pm
S1:

0 < 1 - (y/x)

0 < (x - y)/x

If x > 0, then we have

0 < x - y

but if 0 > x, we have

0 > x - y

giving us conflicting results; INSUFFICIENT.

S2::

We know nothing about the sign of x; INSUFFICIENT.

S1+S2::

We still know nothing about the sign of x; INSUFFICIENT.