Is x + y < 1 ?
(1) x < 8/9
(2) y < 1/8
IMO: E
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
xy
This topic has expert replies
GMAT/MBA Expert
-
Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
We know that 8/9 + 1/9 = 1GmatKiss wrote:Is x + y < 1 ?
(1) x < 8/9
(2) y < 1/8
IMO: E
Since 1/8 > 1/9, we can see that 8/9 + 1/8 > 1
So, if x and y are just slightly less than 8/9 and 1/8 respectively, their sum will be greater than 1.
Conversely, x and y could both equal 0, in which case their sum will be less than 1.
So, the answer must be E
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
GMAT/MBA Expert
-
Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
We can also answer the question, by showing two contradicting cases.GmatKiss wrote:Is x + y < 1 ?
(1) x < 8/9
(2) y < 1/8
IMO: E
Aside: 8/9 = 640/720 and 1/8 = 90/720
If x < 8/9 and y < 1/8 then we could have the following two cases:
case a: x = 639/720 and y = 89/720
In this case, x+y > 1
case b: x = 0 and y = 0
In this case, x+y < 1
Since we cannot answer the target question with certainty, the answer is E
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
-
GMATGuruNY
- 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
GmatKiss wrote:Is x + y < 1 ?
(1) x < 8/9
(2) y < 1/8
IMO: E
Statement 1: x < 8/9.
No information about y.
INSUFFICIENT.
Statement 2: y < 1/8.
No information about x.
INSUFFICIENT.
Statements 1 and 2 combined:
Adding together the two inequalities, we get:
x+y < 8/9 + 1/8
x+y < 64/72 + 9/72
x+y < 73/72.
If x+y = 72/72, then x+y=1.
If x+y = 1/72, then x+y<1.
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
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
