GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 23 Jul 2018, 08:52

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

If x and y are integers, is (x−1)>y?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

2 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 10 Apr 2012
Posts: 277
Location: United States
Concentration: Technology, Other
GPA: 2.44
WE: Project Management (Telecommunications)
GMAT ToolKit User Premium Member
If x and y are integers, is (x−1)>y?  [#permalink]

Show Tags

New post 04 Feb 2014, 15:43
2
4
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

48% (01:18) correct 52% (06:48) wrong based on 241 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
Intern
Intern
avatar
Joined: 27 May 2012
Posts: 1
Doubt in a DS question  [#permalink]

Show Tags

New post 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
Expert Post
Magoosh GMAT Instructor
User avatar
G
Joined: 28 Dec 2011
Posts: 4667
Re: Doubt in a DS question  [#permalink]

Show Tags

New post 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

Image

Image

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

Expert Post
2 KUDOS received
Magoosh GMAT Instructor
User avatar
G
Joined: 28 Dec 2011
Posts: 4667
Re: If X and y are integers, is (x−1)>y?  [#permalink]

Show Tags

New post 04 Feb 2014, 18:21
2
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

Image

Image

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

1 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 10 Apr 2012
Posts: 277
Location: United States
Concentration: Technology, Other
GPA: 2.44
WE: Project Management (Telecommunications)
GMAT ToolKit User Premium Member
Re: If x and y are integers, is (x−1)>y?  [#permalink]

Show Tags

New post 05 Feb 2014, 05:50
1
1
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 x-1 equal to y, not greater. So because you can still get "no" and "yes", the correct answer is E.
Intern
Intern
avatar
Joined: 22 Feb 2014
Posts: 27
GMAT ToolKit User
Re: If x and y are integers, is (x−1)>y?  [#permalink]

Show Tags

New post 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 x-1 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
Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 47221
Re: If x and y are integers, is (x−1)>y?  [#permalink]

Show Tags

New post 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 x-1 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: Ultimate GMAT Quantitative Megathread | 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?
Extra-hard Quant Tests with Brilliant Analytics

1 KUDOS received
SVP
SVP
User avatar
Joined: 06 Sep 2013
Posts: 1865
Concentration: Finance
GMAT ToolKit User
Re: If x and y are integers, is (x−1)>y?  [#permalink]

Show Tags

New post 01 Jun 2014, 07:58
1
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

x-y / 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
Expert Post
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 5878
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Re: If x and y are integers, is (x−1)>y?  [#permalink]

Show Tags

New post 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 a-x>b-x
3) a>b and c>d --> a+c>b+d 4) a>0 --> 2a>0, a<0 --> 2a<a 5) -1<0<1 --> a-1<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 one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Senior Manager
Senior Manager
avatar
S
Joined: 15 Jan 2017
Posts: 365
CAT Tests
Re: If x and y are integers, is (x−1)>y?  [#permalink]

Show Tags

New post 03 Oct 2017, 14:14
Narrow miss. Almost picked A. But there is always the 'language' red flag.
St 1: x is a positive multiple of y.
I immediately thought y is negative. In that case, asper number line; x - 1> y (on the left of zero). But what if y is positive? Then I am not sure, cause no values are given.

St 2:x/y> 1 so x> y. But is x -1> y? I am not sure again.

1) + 2) = ultimately I am not clear about the direction of x and y: which one is left of zero or right; or are both in the same direction. So cannot conclude x-1>y

So picked E as no particular answer was sufficient, even after combining.
Re: If x and y are integers, is (x−1)>y? &nbs [#permalink] 03 Oct 2017, 14:14
Display posts from previous: Sort by

If x and y are integers, is (x−1)>y?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  

Events & Promotions

PREV
NEXT


GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.