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# Is x+y < 1 ? (1) x < 8/9 (2) y < 1/8

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Is x+y < 1 ? (1) x < 8/9 (2) y < 1/8 [#permalink]  04 Apr 2006, 11:00
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68% (01:41) correct 31% (00:51) wrong based on 0 sessions
Is x+y < 1 ?

(1) x < 8/9
(2) y < 1/8

OPEN DISCUSSION OF THIS QUESTION IS HERE: is-x-y-1-1-x-8-9-2-y-129557.html
[Reveal] Spoiler: OA
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Director
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vivek123 wrote:
Is x+y < 1 ?

(1) x < 8/9
(2) y < 1/8

1) x<64/72

2) y<9/72

Alone obviously insufficient

x+y<73/72, so it can be greater or smaller than 1

E
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Director
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GMATPrep DS: x+y<1? [#permalink]  12 May 2006, 05:10
Is x+y<1?

1) x<8/9
2) y<1/8
Senior Manager
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I'd go for C.
Director
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From (1) dont know y so cannot say - not sufficient

From (2) dont know x so cannot say - not sufficient

Combining both:

8/9 + 1/8 = 73/72 ... so x+y could be greater than 1 (as it can be 145/144 which is less than 73/72 but greater than 1) or less than 1

So I will go with E
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Re: GMATPrep DS: x+y<1? [#permalink]  12 May 2006, 12:04
Professor wrote:
M8 wrote:
Is x+y<1?
1) x<8/9
2) y<1/8

C...

why i am overlooking so frequently????????????? i must be rushing. its not good practice to work and practice gmat..

Last edited by Professor on 12 May 2006, 12:57, edited 1 time in total.
Director
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But prof, don't psych me like that i work too!
VP
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Yep its E!!
Director
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gmatmba wrote:
From (1) dont know y so cannot say - not sufficient

From (2) dont know x so cannot say - not sufficient

Combining both:

8/9 + 1/8 = 73/72 ... so x+y could be greater than 1 (as it can be 145/144 which is less than 73/72 but greater than 1) or less than 1

So I will go with E

Buddy x<8/9 and y<1/8, so you should add fractions lower than these ones to check. And 145/144 is greater than 1 as well.
Director
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Hi M8

My reasoning is that if x=8/9 and y=1/8, then (x+y) will equal 73/72 which is > 1.

Now since there are many other values between 1 and 73/72 (like 145/144 for eg) that is greater than 1 but less than 73/72, there are possible values of (x+y) such that 1 < (x+y) < 73/72

From here, we can find values of x such that x < 8/9
and find values of y such that y < 1/8
and their total (x+y) < 73/72 but still > 1

Hope this explains better, please let me know.

BTW, what is OA? What is the source?
Director
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gmatmba wrote:
BTW, what is OA? What is the source?

OA is E, it's GMATPrep question.

Thks buddy I got it now.
Intern
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Quick approach
x= 8/9 , y = 1/8

8/9 + 1/9 = 1
1/8 > 1/9

Therefore 8/9 + 1/8 > 1...x + y > 1
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GMAT Prep DS - number properties [#permalink]  08 Aug 2006, 08:06
is x + y < 1?

1. x < 8/9
2. y < 1/8
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Re: GMAT Prep DS - number properties [#permalink]  08 Aug 2006, 08:13
gmatinjune wrote:
is x + y < 1?

1. x < 8/9
2. y < 1/8

x < 8/9 => y < 1/9
y < 1/8 => x < 7/8

But, there exists solutions for

7/8 < x < 8/9
1/9 < y < 1/8

For example, if x = .88 and y = .12, it satisifes (1) and (2) but the inequality fails to hold.

So, FALSE.

(I admit that I'm unfamiliar with the A/B/C/D/E schism for these types of questions, please forgive me.)
SVP
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Hello everyone , allow me to try to solve this problem with you .

My try is as follows:

a) x<8/9

ie: x<1-(1/9) means x+(1/9)<1.......... not sufficient

b) y<1/8 not suffecient

Taking a,b together we only need to compare y and 1/9.

ie 1/8 , 1/9 ... 1/8>1/9 therfore y could be 1/9 ( ie any value less than 1/8)

from a we only need to know if y could be = 1/9 ( we dont know this from b)
CEO
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E
St1: Clearly INSUFF

St2: Clearly INSUFF

Combined
x + y < 73/72

so it may be littlle greater than 1 or less than 1. INSUFF
_________________

SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008

Manager
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I have a question
Why not C?

Stem 1 says x is less than 8/9
So x is either = to 7/9 or 8/10 or something LESS than that right?

Y is = less than 1/8. I can't think of any combination where if both of these are true, the sum is greater than 1

I think I had this p roblem on GMAT prep and got it right on Sunday..

But I could be mistaken.
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b/w C and E

I picked C because I got 8/9+1/8=73/72... but both statements say that x and y has got to be less than 8/9 and 1/8... so must be less than 73/72...

for this kind of questions... is the strategy to always add the numbers given or pick the values close to 8/9 and 1/8 that are less???
Manager
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I usually prefer not to pick numbers but I think it works here..
As I said, the only numbers less than 8/9 are 8/10 or 7/9. Either way you would need at least 1/10 to get to 1 at that point. Hence C , IMO
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