Author 
Message 
TAGS:

Hide Tags

Intern
Status: Aiming for 750+
Joined: 16 Oct 2013
Posts: 21
GMAT Date: 05052014

What is y? [#permalink]
Show Tags
13 Dec 2013, 15:31
Question Stats:
58% (00:54) correct 43% (00:36) wrong based on 119 sessions
HideShow timer Statistics
What is y? (1) x  y = 1 (2) xy = 12 I understand the question but my doubt however is: The MGMAT Guide says, Quote: Even when the equations are combined, they do not provide enough information to find y, and the answer is (E). . I do not understand why it says that because when I combine both the equations, I get a quadratic equation. I solve it and I get two answers y = 4 or y = 3. So, my take is using both the equations I am able to find the value of y. So, why is the correct answer E and why not C? Thank you!
Official Answer and Stats are available only to registered users. Register/ Login.



Intern
Joined: 05 Oct 2013
Posts: 21

Re: What is y? (1) x  y = 1 (2)x y = 12 [#permalink]
Show Tags
14 Dec 2013, 03:36
1
This post received KUDOS
flower07 wrote: What is y? (1) x  y = 1 (2)x y = 12 I understand the question but my doubt however is: The MGMAT Guide says, Quote: Even when the equations are combined, they do not provide enough information to find y, and the answer is (E). . I do not understand why it says that because when I combine both the equations, I get a quadratic equation. I solve it and I get two answers y = 4 or y = 3. So, my take is using both the equations I am able to find the value of y. So, why is the correct answer E and why not C? Thank you! You got two possible values of y, which means that you don't know which one must be y (only one value counted!). The answer should be E



Math Expert
Joined: 02 Sep 2009
Posts: 43851

Re: What is y? [#permalink]
Show Tags
14 Dec 2013, 05:12
flower07 wrote: What is y? (1) x  y = 1 (2) xy = 12 I understand the question but my doubt however is: The MGMAT Guide says, Quote: Even when the equations are combined, they do not provide enough information to find y, and the answer is (E). . I do not understand why it says that because when I combine both the equations, I get a quadratic equation. I solve it and I get two answers y = 4 or y = 3. So, my take is using both the equations I am able to find the value of y. So, why is the correct answer E and why not C? Thank you! When a DS question asks about the value of some variable, then the statement is sufficient ONLY if you can get the single numerical value of this variable. Since you get TWO possible values of y, the statements are not sufficient. Hope it's clear.
_________________
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? Extrahard Quant Tests with Brilliant Analytics



Manager
Status: Work hard in silence, let success make the noise
Joined: 25 Nov 2013
Posts: 156
Location: India
Concentration: Finance, General Management
GMAT 1: 540 Q50 V15 GMAT 2: 640 Q50 V27
GPA: 3.11
WE: Consulting (Computer Software)

Re: What is y? [#permalink]
Show Tags
14 Dec 2013, 10:01
1
This post received KUDOS
I marked E since we are getting 2 values of y(3,4) even after combining both the equations.
_________________
Sahil Chaudhary If you find this post helpful, please take a moment to click on the "+1 KUDOS" icon. My IELTS 7.5 Experience From 540 to 640...Done with GMAT!!! http://www.sahilchaudhary007.blogspot.com



Director
Joined: 12 Nov 2016
Posts: 790

Re: What is y? [#permalink]
Show Tags
24 May 2017, 11:33
flower07 wrote: What is y? (1) x  y = 1 (2) xy = 12 I understand the question but my doubt however is: The MGMAT Guide says, Quote: Even when the equations are combined, they do not provide enough information to find y, and the answer is (E). . I do not understand why it says that because when I combine both the equations, I get a quadratic equation. I solve it and I get two answers y = 4 or y = 3. So, my take is using both the equations I am able to find the value of y. So, why is the correct answer E and why not C? Thank you! You just have to pay attention to the mild trap this question is baiting you into  it wants to make sure you are remembering the commutative instead of making assumptions. For example, (4)3= 12 43 = 1 BUT 3(4)=12 3 4= 1



Director
Joined: 12 Nov 2016
Posts: 790

Re: What is y? [#permalink]
Show Tags
08 Sep 2017, 19:35
flower07 wrote: What is y? (1) x  y = 1 (2) xy = 12 I understand the question but my doubt however is: The MGMAT Guide says, Quote: Even when the equations are combined, they do not provide enough information to find y, and the answer is (E). . I do not understand why it says that because when I combine both the equations, I get a quadratic equation. I solve it and I get two answers y = 4 or y = 3. So, my take is using both the equations I am able to find the value of y. So, why is the correct answer E and why not C? Thank you! Nice trick here...classic "C" trap St 1 xy =1  clearly too many possibilities insuff St 2 xy = 12 clearly too many possibilities insuff St 1 and St 2 This question wants you to assume that the answer should be 4 and 3...however the answer can also be 3 and 4 E










