Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 64125

Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
20 Dec 2015, 05:37
Question Stats:
66% (01:15) correct 34% (01:15) wrong based on 233 sessions
HideShow timer Statistics
Math Revolution and GMAT Club Contest Starts! QUESTION #15:If x and y are integers, are they consecutive? (1) x + y = 2 (2) x  y = 4 Check conditions below: Math Revolution and GMAT Club ContestThe Contest Starts November 28th in Quant Forum We are happy to announce a Math Revolution and GMAT Club Contest For the following four (!) weekends we'll be publishing 4 FRESH math questions per weekend (2 on Saturday and 2 on Sunday). To participate, you will have to reply with your best answer/solution to the new questions that will be posted on Saturday and Sunday at 9 AM Pacific. Then a week later, the forum moderator will be selecting 2 winners who provided most correct answers to the questions, along with best solutions. Those winners will get 6months access to GMAT Club Tests. PLUS! Based on the answers and solutions for all the questions published during the project ONE user will be awarded with ONE Grand prize: PS + DS course with 502 videos that is worth $299! All announcements and winnings are final and no whining GMAT Club reserves the rights to modify the terms of this offer at any time. NOTE: Test Prep Experts and Tutors are asked not to participate. We would like to have the members maximize their learning and problem solving process.
Thank you!
Official Answer and Stats are available only to registered users. Register/ Login.
_________________



Intern
Joined: 12 Jul 2015
Posts: 17
Location: United States
Concentration: Strategy, General Management
WE: General Management (Pharmaceuticals and Biotech)

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
20 Dec 2015, 06:17
Given: x and y are integers,
Question: are they consecutive? => x=y+1 or x=y1
First Approach by Substituting numbers (1) x + y = 2 eg 1: 1+1=2 eg 2: 0+2=2 or 2+0=2 eg 3: 1+3=2 etc We see that in any case x and y are not consecutive. Hence sufficient
(2) x  y = 4 eg 1: 8  4 = 4 eg 2: 4  0 = 4 or 0  (4) =4 eg 3: 2(2)=4 We see that in any case x and y are not consecutive. Hence sufficient
Second Approach: (1) x + y = 2 0r x = 2  y(1) If x and y are consecutive, x=y+1 or x=y1 (ie x>y and y>x) Case 1: On substituting for x = y+1 in (1) 2y = y+1 y = 1/2  Not an integer Case 2: On substituting for x=y1 2y=y1 y=3/2 Not an Integer
Hence, they do not satisfy the conditions, x and y are not consecutive.
(2) x  y = 4 Or x = 4+y If x and y are consecutive, x=y+1 or x=y1 but x= 4+y indicates that they are not consecutive
Hence D



Intern
Joined: 30 Sep 2013
Posts: 20

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
20 Dec 2015, 07:23
Here I was having the doubt weather it is consecutive integers or is it even consecutive integers or is it odd consecutive integers .
I have assumed that it is consecutive integers i.e x and x + 1
Y = X + 1 ? Though they are number of ways to solve this . We can keep this value and test it or any other approach .
Statement (1) x + y = 2
The sum of any two consecutive integers is odd. For example ,
X = 1 , Y = 0 then X + Y is 1 which is odd. X = 1 , Y = 0 then X + Y is 1 which is odd. X = 1 , Y = 2 then X + Y is 3 which is odd. X = 11 , Y = 12 then X + Y is 23 which is odd.
So they are not consecutive integers. may be they both are equal integers i.e X =1 and Y = 1
If the question was about even consecutive integers , then there would be chances that x = 0 and y = 2 Then x,y would be consecutive. But my current assumption is with normal consecutive integer.
(2) x  y = 4
The difference between any two consecutive integers is 1 So they are not consecutive integers.
Answer is D



Director
Joined: 20 Feb 2015
Posts: 722
Concentration: Strategy, General Management

Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
Updated on: 27 Dec 2015, 23:24
for x and y to be consecutive either x=y+1 or x=y1 since neither of the statement doesn't give the required condition for x and y to be consecutive so D
Originally posted by CounterSniper on 20 Dec 2015, 07:34.
Last edited by CounterSniper on 27 Dec 2015, 23:24, edited 2 times in total.



Intern
Joined: 20 Jan 2015
Posts: 44

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
20 Dec 2015, 10:09
option D. We need to find yes or no.
Statement 1 We cannot get any consecutive values of integer x and y such that x+y=2 The only close value is when both are equal i.e. x=1 and y=1 but still they are not consecutive. => no. => sufficient. Statement 2 We cannot get any consecutive values of integer x and y such that xy=4 => no => sufficient.
Answer option D.



Intern
Joined: 21 Jan 2013
Posts: 36
Concentration: General Management, Leadership
GPA: 3.82
WE: Engineering (Computer Software)

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
20 Dec 2015, 10:14
QUESTION #15:
If x and y are integers, are they consecutive?
(1) x + y = 2 (2) x  y = 4
 (1) x+y = 2 the sum of any two consecutive integers is always ODD, so if sum of x and y is 2 (even), they cannot be consecutive, SUFFICIENT. (2) xy = 4 x is 4 units to the right to y on number line., so they are not consecutive. SUFFICIENT. answer choice : D



Intern
Joined: 01 Nov 2015
Posts: 29
Location: India
Concentration: Marketing, Entrepreneurship
WE: Engineering (Computer Software)

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
20 Dec 2015, 20:50
I. x + y = 2 =>
Let's try some numbers  1+1 = 2 (Not Consecutive) 0+2 = 2 (NC) 1+3=2 (NC)
We can see that x and y cannot be consecutive and solve the equation Sufficient
II. xy=4 x = y + 4 i.e; x is greater than y by 4 hence they are not concecutive Sufficient
Answer is D



Intern
Joined: 09 Jul 2015
Posts: 44

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
21 Dec 2015, 17:00
Answer is D. Both statements are sufficient to answer the question.
if x & y are integers, are they consecutive ?
1) x+y = 2  this means both x and y are odd or both x and y are even as the result is even. This will never be possible if they are consecutive. Hence x and y are not consecutive. SUFFICIENT.
2) xy=4  same logic as above, either x and y both should be odd or both should be even for this to be true. Hence x and y are not consecutive. SUFFICIENT.
Answer is D  both are sufficient



Manager
Status: single
Joined: 19 Jan 2015
Posts: 80
Location: India
GPA: 3.2
WE: Sales (Pharmaceuticals and Biotech)

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
21 Dec 2015, 19:27
if x and y are consecutive integers
If both integers are positive, then add a,a+1=2a+1,
If both integers are negative, then add= aa1=2a1.
If consecutive integers substract then, aa1=1
or a+a1=1., if we use 0 and add equals 1 or 1
if we substitue addition in statment 1 and substraction statement 2 not satisfy as integers.
so both statements are sufficient that x and y are not consecutive integers.
so option D is correct.



Manager
Joined: 07 May 2015
Posts: 172
Location: India
GPA: 3

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
21 Dec 2015, 19:57
statement 1: x+y = 2 this will be true for values: 1+1 =2 or 31 = 2 or 42 = 2 Thus in all cases x and y are not consecutive Sufficient
Statement 2: x y = 2 this will be true for values : 51 = 4or 3+1 =4 or 2+2=4 or 4+8 = 4. Thus in all cases x and y are not consecutive Sufficient
Ans: D



Marshall & McDonough Moderator
Joined: 13 Apr 2015
Posts: 1675
Location: India

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
22 Dec 2015, 01:16
St1: x + y = 2 If two integers are consecutive, one integer has to be even and the other integer has to be odd. even + odd = odd. But according to statement 1, the sum of two integers is even. > x and y are not consecutive integers. Statement 1 alone is sufficient.
St2: x  y = 4. The 2 integers differ by 4 and hence are not consecutive integers. Also, if x and y are consecutive, the difference between the 2 integers should be odd. But, since the difference is even x and y are not consecutive integers. Statement 2 alone is sufficient
Answer: D



Intern
Joined: 21 Nov 2014
Posts: 25
Location: Viet Nam

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
22 Dec 2015, 03:20
(1) x + y = 2 Since two consecutive integers contain 1 odd number and one even number, sum of two consecutive integers is always odd. > x & y are not consecutive. Sufficient. (2) x  y = 4 Since the different between two consecutive integers is always either 1 or  1, it is sufficient to conclude that x & y are not consecutive. Answer D.
_________________
GMAT Group for Vietnamese:
https://www.facebook.com/groups/644070009087525/



Intern
Joined: 30 Oct 2015
Posts: 9
Location: United States
Concentration: Finance, Technology
WE: Information Technology (Investment Banking)

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
22 Dec 2015, 19:02
D I No two consecutive integers can sum up to 2 II Two consecutive integers will either have a difference of +1 or 1.



Senior Manager
Joined: 23 Sep 2015
Posts: 362
Location: France
GMAT 1: 690 Q47 V38 GMAT 2: 700 Q48 V38
WE: Real Estate (Mutual Funds and Brokerage)

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
23 Dec 2015, 06:57
1) The sum of two consecutive integers is always ODD. If both x and y and negative, the sum will be a negative odd, if both positive, a positive odd is one of them is zero then the sum is 1 or 1. Sufficient x and y are not consecutive integers 2) The difference of 2 consecutive integers is always 1 or 1  if x is 3 and y 4 ==> 1 if x is 4 y 3 ==> 1  if x is 3 y 4 ==> 1  if x is 4 y 3 ==> 1 Sufficient x and y are not consecutive Answer D
_________________



Intern
Joined: 17 Aug 2014
Posts: 10

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
24 Dec 2015, 02:58
Either statement alone is sufficient to answer this question The answer is no. The numbers are not consecutive x+y=2, by trial and error we can notice that none of the combinations are consecutive(1,1),(0,2),(2,0),(3,1),(1,3),(4,2),(2,4) and so on
By statement 2 , xy=4, we can infer that x and y are seperated by 4 places on the number line and hence are not consecutive.
Ans) D



Intern
Joined: 05 Jun 2013
Posts: 25

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
25 Dec 2015, 05:01
x and y are integers, are they consecutive?
(1) x + y = 2 Lets say x , y are consecutive. Then their difference will be 1 .Therefore y should be either equal to x+1 or x1 x+x+1 = 2 2x =1 x=1/2. Given x is integer. So not possible. x+x1= 2 2x=3 x=3/2 Given x is integer. So not possible. Therefore with this equation, x and y can never be consecutive. So sufficient.
(2) x  y = 4 Lets say x , y are consecutive. Then their difference will be 1 . which means x y=1 or yx =1 . Therefore x and y are not consecutive from this above equation. Hence sufficient.
As EACH statement ALONE is sufficient to answer the question asked, therefore choice D.



Retired Moderator
Joined: 21 Jun 2014
Posts: 1074
Location: India
Concentration: General Management, Technology
GPA: 2.49
WE: Information Technology (Computer Software)

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
25 Dec 2015, 13:17
Given: x and y are integers(1) x + y = 2 sum of two consecutive integers will not be 2. Sufficient. (2) x  y = 4 Difference should be 1 in case of consecutive integers. Sufficient. Option D is the correct answer.
_________________



Math Expert
Joined: 02 Sep 2009
Posts: 64125

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
27 Dec 2015, 11:23
Bunuel wrote: Math Revolution and GMAT Club Contest Starts! QUESTION #15:If x and y are integers, are they consecutive? (1) x + y = 2 (2) x  y = 4 Check conditions below: Math Revolution and GMAT Club ContestThe Contest Starts November 28th in Quant Forum We are happy to announce a Math Revolution and GMAT Club Contest For the following four (!) weekends we'll be publishing 4 FRESH math questions per weekend (2 on Saturday and 2 on Sunday). To participate, you will have to reply with your best answer/solution to the new questions that will be posted on Saturday and Sunday at 9 AM Pacific. Then a week later, the forum moderator will be selecting 2 winners who provided most correct answers to the questions, along with best solutions. Those winners will get 6months access to GMAT Club Tests. PLUS! Based on the answers and solutions for all the questions published during the project ONE user will be awarded with ONE Grand prize: PS + DS course with 502 videos that is worth $299! All announcements and winnings are final and no whining GMAT Club reserves the rights to modify the terms of this offer at any time. NOTE: Test Prep Experts and Tutors are asked not to participate. We would like to have the members maximize their learning and problem solving process.
Thank you! MATH REVOLUTION OFFICIAL SOLUTION:Since we have 2 variables (x, y) in the original condition, we also need 2 equations to match the number of variables and the number of equations. Since we need both 1) and 2), the correct answer is likely C. Using both con 1) & 2), we get x=3, y=1. Since they are not consecutive, it is not sufficient. Therefore the correct answer is C. However, since this is an “integer” question, which is one of the key questions, we should apply Common Mistake Type 4(A). In case of con 1), if x+y=2, in any cases, there cannot be consecutive integers. So this is a “no” and sufficient (Adding two consecutive integers will always yield an odd number). In case of con 2), the difference between two consecutive integers is always 1. So this is also a “no” and sufficient. Therefore, the correct answer is D. If D and C are both correct answers, then D is the final correct answer. This type of question appears in a score range of 50 to 51. Note 1: Solving this type of question usually takes over 5 minutes during the actual exam. However, if you understand the relationship between Variable Approach Method and Common Mistake Types, you will be able to solve this type of question in just about 2 minutes. Note 2: For cases where we need 2 more equations, such as original conditions with “2 variables”, or “3 variables and 1 equation”, or “4 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 70% chance that C is the answer, while E has 25% chance. These two are the majority. 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 using 1) and 2) separately according to DS definition (It saves us time). Obviously there may be cases where the answer is A, B, D or E.
_________________



NonHuman User
Joined: 09 Sep 2013
Posts: 15036

Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
Show Tags
01 Jan 2017, 21:46
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.
_________________




Re: Math Revolution and GMAT Club Contest! If x and y are integers, are
[#permalink]
01 Jan 2017, 21:46




