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ridhamshah
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Post subject: Is x+y < 1?  Posted: Wed Mar 03, 2010 12:13 pm |
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Posts: 6
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Is x+y<1?
(1) x < 8/9
(2) y < 1/8
I thought (c) but the answer is (e).
The way I solved this was x + y = 73/72 > 1, for x=8/9 and y=1/8
If x= 8/9 = 0.8888..and y=1/8 = 0.125
So if x<8/9 and y<1/8 would mean x+y = 0.88+0.124>1
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luc2r4
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Post subject: Re: Is x+y < 1? Posted: Fri Mar 05, 2010 2:07 am |
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Posts: 14
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Each St1 and St2 is INSUFFICIENT
Each do not give info for x +y < 1
since they provide an inequality just for one of the variables
Together {St1 and St2 } are ALSO INSUFFICIENT
Since x <8/9
y < 1/8 , Summing both inequalities : x+ y < 73/ 72
Draw a number line for x+ y < 73/ 72 and x +y < 1
Then you will see that as we found that x+ y < 73/ 72
At the interval 1 =< x+ y < 73/ 72 we can not conclude that x +y < 1
answer = E
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akhp77
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Post subject: Re: Is x+y < 1? Posted: Sat Mar 27, 2010 3:55 am |
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Statement 1: Insufficient
Statement 2: Insufficient
Statement 1 and 2
x + y < 73/72 = 1 + 1/72
x + y could be 1 + 1/74, 1 + 1/76, 1 + 1/200 , 1, 1/10, 1/16, 20, and so on
So we can't conclude that whether x+y would be greater than, less than, or equal to 1 but we say only that x+y < 1 + 1/72
Insufficient
Ans: E
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StaceyKoprince
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Post subject: Re: Is x+y < 1? Posted: Tue Apr 27, 2010 12:27 pm |
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Posts: 5789
Location: San Francisco
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ridhamshah, I'm wondering whether your difficulty here might not have to do with how the test works (as opposed to the actual math).
They are asking a yes/no question: is x+y<1?
1) If we are given information to let us say "yes, x+y is ALWAYS less than 1" then that information is sufficient.
2) If we are given information to let us say "no, x+y is NEVER less than 1" then that information is sufficient.
3) If we are given information that tells us "sometimes x+y is less than 1 and sometimes x+y is not less than 1" then that information is insufficient.
In your example, you showed how x+y might be greater than 1. You could also choose much smaller numbers for x and y, such that the sum would be less than 1, right? In this case, we have the 3rd scenario listed above: sometimes it's less than 1 and sometimes it's not less than 1.
_________________
Stacey Koprince
Instructor
Director of Online Community
ManhattanGMAT
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anupam.global
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Post subject: Re: Is x+y < 1? Posted: Tue Dec 14, 2010 8:38 am |
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Posts: 2
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Is it correct to do this way?
St1 & St2)
x=LT8/9
y=LT1/8
Therefor x+y = LT8/9 +LT1/8= LT73/72
Hence it could be anything from just little over +1 OR 1 or LT +1 (positive fraction) OR any number/fraction infinetly in the negative.
Please correct me if I am wrong in my understanding. Thanks.
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tim
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Post subject: Re: Is x+y < 1? Posted: Tue Dec 14, 2010 9:40 am |
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Posts: 1779
Location: Southwest Airlines, seat 21C
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sounds good to me..
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Tim Sanders
Manhattan GMAT Instructor
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veta
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Post subject: Re: Is x+y < 1? Posted: Sat Feb 19, 2011 6:23 am |
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akhp77 wrote: Statement 1: Insufficient
Statement 2: Insufficient
Statement 1 and 2
x + y < 73/72 = 1 + 1/72
x + y could be 1 + 1/74, 1 + 1/76, 1 + 1/200 , 1, 1/10, 1/16, 20, and so on
So we can't conclude that whether x+y would be greater than, less than, or equal to 1 but we say only that x+y < 1 + 1/72
Insufficient
Ans: E I don't think x+y cound be 20
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jnelson0612
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Post subject: Re: Is x+y < 1? Posted: Sat Feb 19, 2011 10:45 pm |
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veta wrote: akhp77 wrote: Statement 1: Insufficient
Statement 2: Insufficient
Statement 1 and 2
x + y < 73/72 = 1 + 1/72
x + y could be 1 + 1/74, 1 + 1/76, 1 + 1/200 , 1, 1/10, 1/16, 20, and so on
So we can't conclude that whether x+y would be greater than, less than, or equal to 1 but we say only that x+y < 1 + 1/72
Insufficient
Ans: E I don't think x+y cound be 20 You are right. I suspect that's a typo.
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Jamie Nelson
ManhattanGMAT Instructor
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