Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 45455

Is xy > 16? [#permalink]
Show Tags
21 Feb 2016, 10:08
Question Stats:
74% (00:41) correct 26% (00:35) wrong based on 290 sessions
HideShow timer Statistics



Intern
Joined: 15 Feb 2016
Posts: 10

Re: Is xy > 16? [#permalink]
Show Tags
21 Feb 2016, 10:58
Neither 1 nor 2 is sufficient. The x could be negative in either case 1 or 2. If x is negative and y is not, the product will surely be less than 16.



Intern
Joined: 27 Apr 2015
Posts: 13

Re: Is xy > 16? [#permalink]
Show Tags
21 Feb 2016, 22:18
1
This post received KUDOS
1
This post was BOOKMARKED
for xy > 16 , x and y should have similar signs.
1) 1 < x < 4 means that x can be either (1.2,1.3,1.4.......,3.9) or x can be (1.1,1.2,1.3....,3.9) and value of y is not provided hence not sufficient.
2) y > 16 provides us the value of y but we donot know the value of x. hence not sufficient.
Combining 1 and 2 we are not sure about the sign of x as x can be +ve or ve.
Thus E is the answer.



Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 5452
GPA: 3.82

Re: Is xy > 16? [#permalink]
Show Tags
21 Feb 2016, 22:20
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. Is xy > 16? (1) 1 < x < 4 (2) y > 16 In the original condition, there are 2 variables(x,y), which should match with the number of equations. So you need 2 equations. However, for 1) 1 equation, for 2) 1 equation, which is likely to make C the answer. When 1) & 2), x=2, y=18 > yes, x=2, y=18 > no, which is not sufficient. Therefore, the answer is E. 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.
_________________
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. "Only $79 for 3 month Online Course" "Free Resources30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons  try it yourself"



Manager
Joined: 07 May 2015
Posts: 175
Location: India
GPA: 3

Re: Is xy > 16? [#permalink]
Show Tags
22 Feb 2016, 00:59
St1: value of x can be anything from 1.1 to 3.9 or 1.1 to 3.9 and there is no clue about y Insufficient
St:2 y>16 if x = 2 then xy = 32 > 16 if x = 2 then xy = 32<16 insufficient
St 1+2: still value of x is not clear
This Ans: E



SVP
Joined: 26 Mar 2013
Posts: 1645

Re: Is xy > 16? [#permalink]
Show Tags
22 Feb 2016, 03:36
Bunuel wrote: Is xy > 16?
(1) 1 < x < 4 (2) y > 16
Kudos for correct solution. 1) No info about Y......Insuf 2) No info about X......Insuf Combine 1&2 X=2 Y= 17.....XY=34>16 X=2 Y=17.....XY=34<16 Answer: E



Manager
Joined: 12 Jun 2016
Posts: 221
Location: India
Concentration: Technology, Leadership
WE: Sales (Telecommunications)

Is xy > 16? [#permalink]
Show Tags
Updated on: 20 Sep 2017, 21:35
Here's My solution Stem: Is XY > 16. (Note: No constraints given. Both X and y could be positive, Negative, Zero, Integer, Non integer) S1: 1 < x < 4 Tells us X = any number on the number line between 1 and 4 or any number on number line between 1 and 4. Also no information on Y. Insuff S2: Y > 16 Tells us Y could be anything from 16 to Infinity. However no info on X. If X = 0 or negative XY is less then 16 and if X is 1, XY = 16 and if X is positive and greater then 1 XY is greater then 16. Insuff S1+S2: X is any number on the number line between 1 and 4 or 1 and 4. Y is greater then 16. XY is less then 16 is X is negative. Its more then 16 if x is positive. Insuff Final Answer : EBunuel wrote: Is xy > 16?
(1) 1 < x < 4 (2) y > 16
Kudos for correct solution.
_________________
My Best is yet to come!
Originally posted by susheelh on 29 Jun 2017, 10:40.
Last edited by susheelh on 20 Sep 2017, 21:35, edited 1 time in total.



Verbal Forum Moderator
Joined: 19 Mar 2014
Posts: 974
Location: India
Concentration: Finance, Entrepreneurship
GPA: 3.5

Re: Is xy > 16? [#permalink]
Show Tags
29 Jun 2017, 14:22
Is \(xy > 16\)? \((1) 1 < x < 4\) This equation does not tell us anything about \(y\) and \(y\) can take any possible value. Hence, (1) =====> is NOT SUFFICIENT\((2) y > 16\) This equation does not tell us anything about \(x\) and \(x\) can take any possible value. Hence, (2) =====> is NOT SUFFICIENTCombining (1) & (2) We know y > 16 And, x can be 3, 2 or 3 & 2 As x can take both positive and negative values, the we will get answer to the question \(xy > 16\) as TRUE and FALSE Hence, Combined (1) & (2) =====> is NOT SUFFICIENTHence, Answer is E
_________________
"Nothing in this world can take the place of persistence. Talent will not: nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not: the world is full of educated derelicts. Persistence and determination alone are omnipotent."
Best AWA Template: https://gmatclub.com/forum/howtoget60awamyguide64327.html#p470475



Manager
Joined: 22 Nov 2016
Posts: 236
Location: United States
Concentration: Leadership, Strategy
GPA: 3.4

Is xy > 16? [#permalink]
Show Tags
20 Sep 2017, 15:07
Statement 1) 1 < x < 4 No information about Y. Insufficient. AD BCEStatement 2) Y > 16 No information about X. Insufficient. B CEUsing 1 and 2. X = 1 and Y=20; Thus XY < 16 or X = 2 and Y=20; XY = 40; Thus XY > 16 Answer is E
_________________
Kudosity killed the cat but your kudos can save it.



Director
Status: It's near  I can see.
Joined: 13 Apr 2013
Posts: 969
Location: India
Concentration: International Business, Operations
GPA: 3.01
WE: Engineering (Consulting)

Re: Is xy > 16? [#permalink]
Show Tags
09 Mar 2018, 03:29
Bunuel wrote: Is xy > 16?
(1) 1 < x < 4 (2) y > 16
Kudos for correct solution. I got it wrong. Question: Is xy > 16? To get this, we need to prove that both x and y have the same sign. St 1: 1 < x < 4 means x can be in between 1 & 4 or 1 & 4 Also we don't know what "y" is? Not SufficientSt 2: y > 16 As we don't know anything about "x", it is Not SufficientCombining St 1 & 2 we don't whether xy > 16 If x is in between 1& 4, answer is YES If x is in between 1 & 4, answer is NO. (E)
_________________
"Success is not as glamorous as people tell you. It's a lot of hours spent in the darkness."



SVP
Joined: 12 Sep 2015
Posts: 2477
Location: Canada

Re: Is xy > 16? [#permalink]
Show Tags
09 Mar 2018, 08:22
Bunuel wrote: Is xy > 16?
(1) 1 < x < 4 (2) y > 16
Target question: Is xy > 16? Statement 1: 1 < x < 4 Since there's no information about y, we cannot determine whether xy is greater than 16Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT Statement 2: y > 16Since there's no information about x, we cannot determine whether xy is greater than 16Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT Statements 1 and 2 combined There are several values of x and y that satisfy BOTH statements. Here are two: Case a: x = 2 and y = 20, in which case xy = 40. In this case, the answer to the target question is YES, xy IS greater than 16Case b: x = 2 and y = 20, in which case xy = 40. In this case, the answer to the target question is NO, xy is NOT greater than 16Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT Answer: E Cheers, Brent
_________________
Brent Hanneson – Founder of gmatprepnow.com










