Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 49858

Question Stats:
74% (00:49) correct 26% (01:16) wrong based on 186 sessions
HideShow timer Statistics



Math Expert
Joined: 02 Sep 2009
Posts: 49858

Re M0105
[#permalink]
Show Tags
16 Sep 2014, 00:14
Official Solution:If \(x \gt 1\) and \(y \gt 1\), is \(x \gt y\)? Notice that we are told that both \(x\) and \(y\) are greater than 1. (1) \(\sqrt{x} \gt y\). Since both parts of the inequality are nonnegative we can safely apply squaring: \(x \gt y^2\). Now, as \(x\) and \(y\) are greater than 1 then \(x \gt y\). Sufficient. Notice that if we were told that \(x \gt 0\) and \(y \gt 0\), instead of \(x \gt 1\) and \(y \gt 1\), then this statement wouldn't be sufficient. For example: if \(x=\frac{1}{3}\) and \(y=\frac{1}{2}\) then \(x=\frac{1}{3} \gt \frac{1}{4}=y^2\) but in this case \(x=\frac{1}{3} \lt \frac{1}{2}=y\). (2) \(\sqrt{y} \lt x\). Square both sides: \(y \lt x^2\). If \(y=2\) and \(x=3\) then the answer to the question is YES, \(x \gt y\) but if \(y=2\) and \(x=2\) then the answer to the question is NO, since in this case \(x=y\). Not sufficient. Answer: A
_________________
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



Intern
Joined: 14 Apr 2014
Posts: 2

Re: M0105
[#permalink]
Show Tags
27 Jan 2015, 07:07
I don't understand why statement 1 can't be deemed insufficient for the same reason as statement 2, i.e. when x=2, and y=2. Why is it possible to use these values when testing statement 2 and not 1?
Posted from my mobile device



Math Expert
Joined: 02 Sep 2009
Posts: 49858

Re: M0105
[#permalink]
Show Tags
27 Jan 2015, 07:11



Intern
Joined: 16 Jan 2015
Posts: 1

Re: M0105
[#permalink]
Show Tags
27 Jan 2015, 09:43
Yes, It does not satisfy the first condition that it √x > y . cos √2 is not greater than 2.
Posted from my mobile device



Manager
Joined: 03 Oct 2014
Posts: 133
Location: India
Concentration: Operations, Technology
WE: Engineering (Aerospace and Defense)

Re: M0105
[#permalink]
Show Tags
28 Jan 2015, 11:53
Hi Bunnuel
I got the correct answer. But in the process, I have got one genuine doubt.
If in any questions we have variables like p, q, r and certain relation is given, is it safe to assume everytime that p can be equal to q can be equal to r??



Math Expert
Joined: 02 Sep 2009
Posts: 49858

Re: M0105
[#permalink]
Show Tags
29 Jan 2015, 05:18



Intern
Joined: 24 Oct 2016
Posts: 6
Concentration: Strategy, Leadership
GPA: 3
WE: Engineering (Manufacturing)

Re: M0105
[#permalink]
Show Tags
27 Dec 2016, 08:33
Hello, I believe that statement 2 is insufficient because of the following:
Statement 2: sqrt(y) < x Rearrangement: y < x^2
Due to this we can determine that Y is less that x^2, but not x alone, for any value of x. This would imply that there are multiple value scenarios where both sufficient and insufficient outcomes could occur.
Additionally when reading the explanation for statement 2, which states x = 2, y = 2 is insufficient, I believe this is meant that y is meant to actually equal four with the resulting sqrt(y) equaling 2. Thus when you use the rearrangement detailed above and plug it in, the result is 4 < 4, which is insufficient.



Intern
Joined: 10 May 2017
Posts: 3

Re: M0105
[#permalink]
Show Tags
16 May 2017, 06:53
The way I came to a conclusion was different from what is given here. But I get this too. I see it is confusing for some people so I'm posting my thought process here. Correct me if I'm wrong.
I just plugged in values and saw the difference.
Statement (1)  \sqrt{x}>y => x>y^2 When you apply statement 1, you always get a situation where x > y let let y = 1.1 or 2, we get x > 1.21 or 4 hence x >y always. SUFFICIENT
Statement (2)  \sqrt{y}<x => y<x^2 When we apply this we don't always get x>y, since x^2 changes drastically if we apply y= 3, x=2 : we see that y < x^2 and y>x but if we apply y=2, x = 3, we get y<x^2 but y<x iNSUFFICIENT



Intern
Joined: 18 Jun 2017
Posts: 11

Re: M0105
[#permalink]
Show Tags
10 Aug 2017, 04:34
In this question, we are supposed to assume the 2 statements as it is. Also the question is asking for is X > Y? i.e. Yes or No
so Statement 1: \sqrt{x} > y it means only those values of x and y which make above statement true. so we can have x and y as follows: X = 3 will have all those values of Y for which Y^2 is less than 3 (so we can have values like Y= 1.41, Y^2 = 2 which answers X > Y as Yes. There is no value of X and Y which satisfies statement1 which will not be able to ans X > Y as Yes or No)
Statement 2: \sqrt{Y} < X i.e. Y^2 < X X = 3 will have Y as 1.73, 1.6, .. >1 as its values. X = 9 will h ave Y as 2, 2.5, 2.6 In this case also we can answer whether X > Y as Yes or No. So answer should be D each statement alone is sufficient.
 Abhishek



Director
Joined: 09 Mar 2016
Posts: 937

Re: M0105
[#permalink]
Show Tags
09 Sep 2017, 11:00
Bunuel wrote: If \(x \gt 1\) and \(y \gt 1\), is \(x \gt y\)?
(1) \(\sqrt{x} \gt y\)
(2) \(\sqrt{y} \lt x\) hi Bunuel , I don't understand why statement 1 can't be deemed insufficient for the same reason as statement 2, i.e. when x=2, and y=2. Why is it possible to use these values when testing statement 2 and not 1 ? can you explain please ?



Math Expert
Joined: 02 Sep 2009
Posts: 49858

Re: M0105
[#permalink]
Show Tags
09 Sep 2017, 11:02



Director
Joined: 09 Mar 2016
Posts: 937

Re: M0105
[#permalink]
Show Tags
10 Sep 2017, 02:11
Bunuel wrote: dave13 wrote: Bunuel wrote: If \(x \gt 1\) and \(y \gt 1\), is \(x \gt y\)?
(1) \(\sqrt{x} \gt y\)
(2) \(\sqrt{y} \lt x\) hi Bunuel , I don't understand why statement 1 can't be deemed insufficient for the same reason as statement 2, i.e. when x=2, and y=2. Why is it possible to use these values when testing statement 2 and not 1 ? can you explain please ? Because x=2, and y=2 do not satisfy \(\sqrt{x} \gt y\). Bunuel thanks for your reply I am still confused .... if x=2, and y=2 dont satisfy \(\sqrt{x} \gt y\), than how can x=2, and y=2 satisfy \(\sqrt{y} \lt x\)[/quote] ? can you please explain in details ? many thanks !



Math Expert
Joined: 02 Sep 2009
Posts: 49858

Re: M0105
[#permalink]
Show Tags
10 Sep 2017, 02:18



SVP
Joined: 26 Mar 2013
Posts: 1837

Bunuel wrote: If \(x \gt 1\) and \(y \gt 1\), is \(x \gt y\)?
(1) \(\sqrt{x} \gt y\)
(2) \(\sqrt{y} \lt x\) Tricky question if we assumed that x & y only integers (1) \(\sqrt{x} \gt y\) Both x & y are positive according to stem. So we can square both sides x > y^2 & by default y^2 > y ...then x > y^2 > y Sufficient (2) \(\sqrt{y} \lt x\) Both x & y are positive according to stem. So we can square both sides y < x^2 Let y =3 & x = 2.........Answer is No Let y =3 & x = 4.........Answer is Yes Insufficient Answer: A



Senior Manager
Joined: 02 Jul 2017
Posts: 294
Concentration: Entrepreneurship, Technology

Re: M0105
[#permalink]
Show Tags
10 Sep 2017, 09:38
Given : x>1 and y>1, so here we don't have to worry about fractions, negative numbers and value 0 and 1 Now find if x>y
Condition 1: \(\sqrt{x}\) >y => x> \(y^2\) Now as we know \(y^2\) >y (if y is not equal to 0 and 1) so => x>\(y^2\) > y => x>y . Answer. Sufficient
by putting values: \(\sqrt{x}\) >y So we have to find value of \(\sqrt{x}\) is "greater" than y. Assume y=2 .. => 2.1 > 2 So \(\sqrt{x}\) = 2.1 => x = 4.41 => 4.41 >2 => x>y Sufficient
Condition 2: \(\sqrt{y}\) < x => y <\(x^2\) => 3<(3)^2 => but here x=y so Answer x> y answer to main question is No => 2< (4)^2 =>Here x> y answer to our main question is yes => 9 < (4)^2 => Here x<y so answer to our main question is No Not sufficient
Answer: A



Manager
Joined: 12 Jun 2016
Posts: 217
Location: India
Concentration: Technology, Leadership
WE: Sales (Telecommunications)

Hello dave13, Let me try and explain how I solved this. It MAY look a bit complex, but once you get a hang of it  this approach is more intuitive (Atleast for me). Stem : Both X and Y are positive. Both of them are not Proper fractions. Question asks, is X > Y? Another way of Paraphrasing this is  On the number line is X on the right of Y? S1: \(\sqrt{X} > Y\) On a Number line, this means \(\sqrt{X}\) is on the right of Y. This is how the Number line would look. Attachment: Case 1.png From this we can very easily infer that X is on the right of Y. Mathematically this means X > Y. Clearly sufficient. S2: \(\sqrt{Y}< X\) What this statement means is, on the number line \(\sqrt{Y}\) is on the left of X. The cases that make this conditions true are Case 1 : Here Y < X Attachment: Case 2.png Case2: : Here Y > X Attachment: Case 3.png S2 gives two Answers for one equation. Hence Insuff. S1 is Sufficient and S2 is Insufficient. The Answer is hence AHope this helps. dave13 wrote: What squaring? Which statement are you talking about? What is unclear? Please be more specific... Bunuel  I am talking about second statement, after squaring both sides to get rid of radical sign why 2 is still 2 and not 2^2 which is 4 http://www.shelovesmath.com/algebra/int ... qualities/ please explain
>> !!!
You do not have the required permissions to view the files attached to this post.
_________________
My Best is yet to come!



Study Buddy Forum Moderator
Joined: 04 Sep 2016
Posts: 1208
Location: India
WE: Engineering (Other)

Re: M0105
[#permalink]
Show Tags
02 Dec 2017, 19:25
Bunuel Quote: (1) \(\sqrt{x} \gt y\). Since both parts of the inequality are nonnegative we can safely apply squaring: \(x \gt y^2\). Now, as \(x\) and \(y\) are greater than 1 then \(x \gt y\). Sufficient. Can you please explain how combining this statement ie. \(x \gt y^2\) along with info in Q stem ie x>1 and y>1 helps us to infer x>y? Did you try to plug in numbers as in St 2? niks18Is Nikkb correct in quoting: Quote: Given : x>1 and y>1, so here we don't have to worry about fractions, negative numbers and value 0 and 1 We can still have x and y as improper fractions, right? say 3/2 which is greater than 1.
_________________
It's the journey that brings us happiness not the destination.



Math Expert
Joined: 02 Sep 2009
Posts: 49858

Re: M0105
[#permalink]
Show Tags
02 Dec 2017, 23:25
adkikani wrote: Bunuel Quote: (1) \(\sqrt{x} \gt y\). Since both parts of the inequality are nonnegative we can safely apply squaring: \(x \gt y^2\). Now, as \(x\) and \(y\) are greater than 1 then \(x \gt y\). Sufficient. Can you please explain how combining this statement ie. \(x \gt y^2\) along with info in Q stem ie x>1 and y>1 helps us to infer x>y? Did you try to plug in numbers as in St 2? niks18Is Nikkb correct in quoting: Quote: Given : x>1 and y>1, so here we don't have to worry about fractions, negative numbers and value 0 and 1 We can still have x and y as improper fractions, right? say 3/2 which is greater than 1. When 0 < x < 1, then x^2 < x. So, squaring decreases the value. For example, (1/2)^2 < 1/2 When x > 1, then x^2 > x. So, squaring increases the value. For example, (3/2)^2 > 3/2
_________________
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










