Kindly let me know how to approach this one?

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kaudes11114: Senior | Next Rank: 100 Posts; Posts: 34; Joined: Tue Nov 12, 2013 8:06 am

by kaudes11114 » Sun Mar 09, 2014 5:06 am

If (x)>(y*y)>(z*z*z*z) which of the following statements could be true?
I. x > y > z
II. z > y > x
III. x > z > y

1. I only
2 I and II only
3. I and III only
4. II and III only
5. I, II, and III

Kindly let me know how to approach this one?

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Source: Beat The GMAT — Data Sufficiency | Sun Mar 09, 2014 5:06 am

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Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Sun Mar 09, 2014 7:30 am

If x > yÂ² > zâ�´, which of the following statements could be true?

I.x > y > z
II. z > y > x
III. x > z > y

A. I only
B. I and II only
C. I and III only
D. II and III only
E. I, II and III

If we CAN find a set of values that satisfies a statement AND yields values such that x > yÂ² > zâ�´, then we'll keep that statement.

Statement I. x > y > z
If x = 2, y = 1, and z = 0, then x > yÂ² > zâ�´
KEEP statement I

Statement II. z > y > x
If x = 1/4, y = 1/3, and z = 1/2, then x > yÂ² > zâ�´
KEEP statement II

Statement III. x > z > y
If x = 2, y = -1, and z = 0, then x > yÂ² > zâ�´
KEEP statement III

Answer: E

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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[email protected]: Elite Legendary Member; Posts: 10392; Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members; Location: Palo Alto, CA; Thanked: 2867 times; GMAT Score:800

by [email protected] » Sun Mar 09, 2014 9:55 pm

Hi kaudes11114,

Brent has provided a great explanation that TESTS VALUES, so I won't rehash that here.

Instead, I'm going to point out the Number Properties that this question is based on. These are "math rules" that are worth knowing, as Number Properties show up on a variety of questions in the Quant section:

1) ANY positive or negative number, when raised to an EVEN INTEGER power, becomes positive.
2) 0, raised to ANY power, is still 0.
3) Positive fractions, when raised to a POSITIVE power GREATER THAN 1, become SMALLER

Number Properties tend to show up in Roman Numeral questions and in DS questions, so keep an eye out for them (and learn them) during your studies.

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

Contact Rich at [email protected]

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theCodeToGMAT: Legendary Member; Posts: 1556; Joined: Tue Aug 14, 2012 11:18 pmFollowed by: 34 members; Thanked: 448 times; GMAT Score:650

by theCodeToGMAT » Sun Mar 09, 2014 10:21 pm

x > y^2 > z^4

Considering x > y^2

this implies x>y or x<y

Similarly..

y^2 > z^4
==> y > z^2 ==> y>z or z>y

Also,

x > z^4
==> x > z^2 or x < z^2
===> x > z or x < z or x < z or x > z

So, I, II and III

R A H U L

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sushantsahaji: Junior | Next Rank: 30 Posts; Posts: 13; Joined: Mon Oct 05, 2015 10:32 am

by sushantsahaji » Sun Jan 17, 2016 7:09 am

theCodeToGMAT wrote:x > y^2 > z^4

Considering x > y^2

this implies x>y or x<y

Similarly..

y^2 > z^4
==> y > z^2 ==> y>z or z>y

Also,

x > z^4
==> x > z^2 or x < z^2
===> x > z or x < z or x < z or x > z

So, I, II and III

How did you get the following?
Considering x > y^2

this implies x>y or x<y

Pls explain this, it may help me.

regards,

sushant

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[email protected]: Elite Legendary Member; Posts: 10392; Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members; Location: Palo Alto, CA; Thanked: 2867 times; GMAT Score:800

by [email protected] » Sun Jan 17, 2016 10:19 am

Hi Sushant,

The prompt does NOT state the variables are integers, so you have to consider the possibility that some of them might be NON-integers.

X > Y^2

Here are two examples that 'fit' this information.... The first is fairly obvious:

X = 2
Y = 1

2 > (1)^2, so X > Y

The second is not quite so obvious....

X = .3
Y = .5

.3 > (.5)^2
.3 > .25

So X < Y

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

Contact Rich at [email protected]

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