Author 
Message 
TAGS:

Hide Tags

Senior Manager
Joined: 10 Apr 2012
Posts: 276
Location: United States
Concentration: Technology, Other
GPA: 2.44
WE: Project Management (Telecommunications)

If x and y are integers, is (x−1)>y? [#permalink]
Show Tags
04 Feb 2014, 15:43
1
This post received KUDOS
3
This post was BOOKMARKED
Question Stats:
43% (02:18) correct
57% (07:02) wrong based on 217 sessions
HideShow timer Statistics
If x and y are integers, is (x−1)>y? (1) x is a positive multiple of y (2) x/y > 1
Official Answer and Stats are available only to registered users. Register/ Login.



Intern
Joined: 27 May 2012
Posts: 1

Doubt in a DS question [#permalink]
Show Tags
04 Feb 2014, 16:58
I recently came across this question and wasn't sure if the answer mentioned in the source was correct. I will appreciate if someone can explain why this answer is correct.
If x and y are integers, is x > y ?
1. x is a positive multiple of y 2. xy > 1



Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4128

Re: Doubt in a DS question [#permalink]
Show Tags
04 Feb 2014, 18:16
akkiankurgupta wrote: I recently came across this question and wasn't sure if the answer mentioned in the source was correct. I will appreciate if someone can explain why this answer is correct.
If x and y are integers, is x > y ?
1. x is a positive multiple of y 2. xy > 1 Dear akkiankurgupta, I'm happy to help. I actually disagree with the OA. The reason I disagree is that any integer is a multiple of itself. For example, 3 is a multiple of 3; in fact, 3 is a positive multiple of 3. Therefore, we could have x = y = 3, and both statements would be true by x would not be greater than y  a "no" answer to the prompt. Of course x = 6 and y = 3 also work, and produce a "yes" answer. I'm not sure the authors considered this technicality  including this, the answer would be (E). Even disregarding this technicality, there's something fishy about statement #1  by the statement " x is a positive multiple of y", do we mean (a) that x is a positive integer that also happens to be a multiple of y, in which cases x = +6 and y = 3 would be possible. or (b) that x is y times some positive integer, in which cases x = 6 and y = 2 Oddly enough, neither of these interpretations, nor the inclusion or exclusion of the technicality above, produce an answer of (C). Something is funny here. Those are my thoughts. Let me know if you have any further questions. Mike
_________________
Mike McGarry Magoosh Test Prep



Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4128

Re: If X and y are integers, is (x−1)>y? [#permalink]
Show Tags
04 Feb 2014, 18:21
guerrero25 wrote: If X and y are integers, is (x−1)>y?
(1)x is a positive multiple of y
(2)x / y > 1 Dear guerrero25, In your understanding, or in the source, what exactly does " positive multiple" mean? In my mind, the statement " x is a positive multiple of y" lends itself to two very different interpretations: (1) x is a positive number and also happens to be a multiple of y; in this case, we could have x = +10 and y = 5 OR (b) x equals y times some positive integer; in this case, we could have x = 10 and y = 5 Of course, either interpretation would be correct with the OA in this question, because x = 15 and y = 3 satisfy both statements and give a "yes" answer to the prompt, and x = 2 and y = 1 satisfy both statements and give a "no" answer to the prompt. Does all this make sense? Mike
_________________
Mike McGarry Magoosh Test Prep



Senior Manager
Joined: 10 Apr 2012
Posts: 276
Location: United States
Concentration: Technology, Other
GPA: 2.44
WE: Project Management (Telecommunications)

Re: If x and y are integers, is (x−1)>y? [#permalink]
Show Tags
05 Feb 2014, 05:50
1
This post was BOOKMARKED
Here is the OE .
Solution: E. This is a great opportunity to play devil's advocate, picking numbers to get "yes" and "no" answers using both statements.
For statement 1, x could be 10 and y could be 1, giving you "yes". But it could also be 1 and 1, so you could get the answer "no".
For statement 2, again x could be 10 and y could be 1, giving you "yes". But you could also have the same with negative numbers, 10 and 1, giving you "no".
The statements together may look to be sufficient (again, 10 and 1 give you "yes"). But 2 and 1 also work, which would make x1 equal to y, not greater. So because you can still get "no" and "yes", the correct answer is E.



Intern
Joined: 22 Feb 2014
Posts: 30

Re: If x and y are integers, is (x−1)>y? [#permalink]
Show Tags
28 Apr 2014, 21:36
guerrero25 wrote: Here is the OE .
Solution: E. This is a great opportunity to play devil's advocate, picking numbers to get "yes" and "no" answers using both statements.
For statement 1, x could be 10 and y could be 1, giving you "yes". But it could also be 1 and 1, so you could get the answer "no".
For statement 2, again x could be 10 and y could be 1, giving you "yes". But you could also have the same with negative numbers, 10 and 1, giving you "no".
The statements together may look to be sufficient (again, 10 and 1 give you "yes"). But 2 and 1 also work, which would make x1 equal to y, not greater. So because you can still get "no" and "yes", the correct answer is E. Hi I dont understand how C is wrong answer here? 2 is not multiple of 1 so how can we use 2 and 1 while combining two statements? What I thought, when we combine both statements then numbers could be X=4 (multiple of 2) Y=2 , 4/2 is greater than 1 so answer comes yes. The same way all multiples give same "yes" answer. We cannt use X=2, Y=2 since it does not satisfy statement 2. Please explain ..how E answer is right not C... Thanks in advance Komal



Math Expert
Joined: 02 Sep 2009
Posts: 39622

Re: If x and y are integers, is (x−1)>y? [#permalink]
Show Tags
29 Apr 2014, 01:19
drkomal2000 wrote: guerrero25 wrote: Here is the OE .
Solution: E. This is a great opportunity to play devil's advocate, picking numbers to get "yes" and "no" answers using both statements.
For statement 1, x could be 10 and y could be 1, giving you "yes". But it could also be 1 and 1, so you could get the answer "no".
For statement 2, again x could be 10 and y could be 1, giving you "yes". But you could also have the same with negative numbers, 10 and 1, giving you "no".
The statements together may look to be sufficient (again, 10 and 1 give you "yes"). But 2 and 1 also work, which would make x1 equal to y, not greater. So because you can still get "no" and "yes", the correct answer is E. Hi I dont understand how C is wrong answer here? 2 is not multiple of 1 so how can we use 2 and 1 while combining two statements? What I thought, when we combine both statements then numbers could be X=4 (multiple of 2) Y=2 , 4/2 is greater than 1 so answer comes yes. The same way all multiples give same "yes" answer. We cannt use X=2, Y=2 since it does not satisfy statement 2. Please explain ..how E answer is right not C... Thanks in advance Komal An integer \(a\) is a multiple of an integer \(b\) means that \(\frac{a}{b}=integer\). Thus since 2/1=2=integer, then 2 IS a multiple of 1. By the way, any integer is a multiple of 1, since 1 is a factor of every integer. Also on the GMAT when we are told that \(a\) is divisible by \(b\) (or which is the same: "\(a\) is a multiple of \(b\)", or "\(b\) is a factor of \(a\)"), we can say that:1. \(a\) is an integer; 2. \(b\) is an integer; 3. \(\frac{a}{b}=integer\).
_________________
New to the Math Forum? Please read this: All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Current Student
Joined: 06 Sep 2013
Posts: 1998
Concentration: Finance

Re: If x and y are integers, is (x−1)>y? [#permalink]
Show Tags
01 Jun 2014, 07:58
1
This post received KUDOS
Is x>y+1?
Statement 1
X is a multiple of y
If y=1 and x=1 answer is NO
If y=1 and x=3 answer is YES
Insufficient
Statement 2
xy / y >0
If y>0 then x>y>0 If y<0 then x<y<0
We could have same cases as above
Statement 1 and 2 combined
We could still have
If y=1 and x=1 answer is NO
If y=1 and x=3 answer is YES
Answer: E



GMAT Club Legend
Joined: 09 Sep 2013
Posts: 15932

Re: If x and y are integers, is (x−1)>y? [#permalink]
Show Tags
18 Sep 2015, 02:06
Hello from the GMAT Club BumpBot! Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up  doing my job. I think you may find it valuable (esp those replies with Kudos). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources



Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 3449
GPA: 3.82

Re: If x and y are integers, is (x−1)>y? [#permalink]
Show Tags
20 Sep 2015, 00:54
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution. If x and y are integers, is (x−1)>y? (1) x is a positive multiple of y (2) x/y > 1 In the original condition there are 2 variables (x,y) and we need 2 equations to match the number of variables and equations. Since there is 1 each in 1) and 2), C has high probability of being the answer. Using both 1) & 2) together (to save time), the answer is no if x=2, y=1, while the answer is yes if x=4, y=1 yes. Therefore the conditions are not sufficient. The answer is E. Normally in case of DS inequality problems, 1) a>b>c > a>b, b>c, a>c 2) a>b > a+x>b+x and ax>bx 3) a>b and c>d > a+c>b+d 4) a>0 > 2a>0, a<0 > 2a<a 5) 1<0<1 > a1<a<a+1 if the problem is not solved using these 5 concepts, E is usually the answer. Normally for cases where we need 2 more equations, such as original conditions with 2 variable, or 3 variables and 1 equation, or 4 variables and 2 equations, we have 1 equation each in both 1) and 2). Therefore C has a high chance of being the answer, which is why we attempt to solve the question using 1) and 2) together. Here, there is 70% chance that C is the answer, while E has 25% chance. These two are the key questions. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since C is most likely to be the answer according to DS definition, we solve the question assuming C would be our answer hence using ) and 2) together. (It saves us time). Obviously there may be cases where the answer is A, B, D or E.
_________________
MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The oneandonly World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. Find a 10% off coupon code for GMAT Club members. “Receive 5 Math Questions & Solutions Daily” Unlimited Access to over 120 free video lessons  try it yourself See our Youtube demo



GMAT Club Legend
Joined: 09 Sep 2013
Posts: 15932

Re: If x and y are integers, is (x−1)>y? [#permalink]
Show Tags
09 Oct 2016, 17:50
Hello from the GMAT Club BumpBot! Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up  doing my job. I think you may find it valuable (esp those replies with Kudos). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: If x and y are integers, is (x−1)>y?
[#permalink]
09 Oct 2016, 17:50







