Is x^3 > y^2? : GMAT Data Sufficiency (DS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 27 Feb 2017, 08:27

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Is x^3 > y^2?

Author Message
TAGS:

### Hide Tags

Senior Manager
Affiliations: SPG
Joined: 15 Nov 2006
Posts: 330
Followers: 14

Kudos [?]: 717 [0], given: 28

### Show Tags

22 May 2010, 23:33
2
This post was
BOOKMARKED
00:00

Difficulty:

35% (medium)

Question Stats:

67% (02:17) correct 33% (01:27) wrong based on 138 sessions

### HideShow timer Statistics

Is x^3 > y^2?

(1) y = x^2
(2) x > x^2
[Reveal] Spoiler: OA

_________________

press kudos, if you like the explanation, appreciate the effort or encourage people to respond.

Math Expert
Joined: 02 Sep 2009
Posts: 37144
Followers: 7266

Kudos [?]: 96779 [1] , given: 10784

### Show Tags

23 May 2010, 01:38
1
KUDOS
Expert's post
dimitri92 wrote:
Is X^3>y^2

1) y=x^2

2) x>x^2

Is $$x^3>y^2$$?

(1) $$y=x^2$$ --> question becomes: is $$x^3>x^4$$? Not sufficient. (For $$0<x<1$$ answer is YES but for other values of $$x$$ answer is NO)

(2) $$x>x^2$$. No info about $$y$$. Not sufficient. But form this statement: $$x^2-x<0$$ --> $$0<x<1$$.

(1)+(2) For any value of $$x$$ from the range $$0<x<1$$ (from 2) inequality $$x^3(1-x)>0$$ holds true. Sufficient.

_________________
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13990
Followers: 592

Kudos [?]: 168 [0], given: 0

Re: Is x^3 > y^2? [#permalink]

### Show Tags

07 Jan 2015, 04:56
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.
_________________
EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 8586
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: 340 Q170 V170
Followers: 400

Kudos [?]: 2567 [0], given: 166

Re: Is x^3 > y^2? [#permalink]

### Show Tags

07 Jan 2015, 11:10
Hi All,

This question can be solved by TESTing VALUES and using the Number Properties that are built-into this question to our advantage.

We're asked if X^3 > Y^2. This is a YES/NO question.

Fact 1: Y = X^2

IF....
X = 0
Y = 0
Is 0^3 > 0^2? The answer to the question is NO.

X = 1/2
Y = 1/4
Is (1/2)^3 > (1/4)^2? The answer to the question is YES.
Fact 1 is INSUFFICIENT

Fact 2: X > X^2

This tells us nothing about Y, so we can quickly deduce that it's insufficient.

However, this info provides us with some serious RESTRICTIONS about X...
X CANNOT be 0
X CANNOT be negative
X CANNOT be greater than or equal to 1
X CAN ONLY BE a POSITIVE FRACTION (that info will come in handy in just a moment).
Fact 2 is INSUFFICIENT.

Combined, we know...
Y = X^2
X is a POSITIVE FRACTION

Under these restrictions, we can rewrite the original question
Is X^3 > Y^2?
as...
Is X(X^2) > X^2?

Since X must be a positive fraction, X^3 will always be SMALLER than X^2, so the answer to the question is ALWAYS NO.
Combined, SUFFICIENT.

[Reveal] Spoiler:
C

GMAT assassins aren't born, they're made,
Rich
_________________

# Rich Cohen

Co-Founder & GMAT Assassin

# Special Offer: Save \$75 + GMAT Club Tests

60-point improvement guarantee
www.empowergmat.com/

***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************

Re: Is x^3 > y^2?   [#permalink] 07 Jan 2015, 11:10
Similar topics Replies Last post
Similar
Topics:
11 Is (-y)/2 > y^2 ? 7 03 Mar 2015, 06:27
2 8x y^3 + 8x^3 y = 2x^2y^2 * 8 , What is xy? (1) y > x (2) 4 31 Mar 2011, 11:00
217 Is x > y ? (1) x^(1/2)>y (2) x^3>y 39 08 Sep 2010, 00:38
29 If y>=0, What is the value of x? (1) |x-3|>=y (2) |x-3|<=-y 21 09 Jan 2010, 13:17
66 If xy 0, is x > y? (1) 4x = 3y (2) |y - x| = x - y 24 12 Nov 2009, 08:45
Display posts from previous: Sort by