Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 05 May 2015, 11:28

### 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

# GMAT Prep 1: PS Q22

Author Message
TAGS:
Manager
Joined: 30 Aug 2007
Posts: 62
Followers: 1

Kudos [?]: 2 [0], given: 0

GMAT Prep 1: PS Q22 [#permalink]  06 Oct 2007, 17:16
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
If x is positive, which of the following could be the correct ordering of 1/x , 2x , and x^2 ?

I. x^2 < 2x < 1/x
II. x^2 < 1/x < 2x
III. 2x < x^2 < 1/x

(a) None
(b) I only
(c) III only
(d) I and II only
(e) I, II and III
VP
Joined: 10 Jun 2007
Posts: 1465
Followers: 6

Kudos [?]: 133 [0], given: 0

Re: GMAT Prep 1: PS Q22 [#permalink]  06 Oct 2007, 17:29
avenger wrote:
If x is positive, which of the following could be the correct ordering of 1/x , 2x , and x^2 ?

I. x^2 < 2x < 1/x
II. x^2 < 1/x < 2x
III. 2x < x^2 < 1/x

(a) None
(b) I only
(c) III only
(d) I and II only
(e) I, II and III

D.
Try x=1/2 for I
Try x=3/4 for II
For III, nothing will work because x^2 > 2x when x is some number greater 1. This means 1/x will be a fraction. This means it won't be greater than 2x.
VP
Joined: 10 Jun 2007
Posts: 1465
Followers: 6

Kudos [?]: 133 [0], given: 0

A little logic for this problem.
If you know graphs well, you can easily find out the answer for this one.

Three graphs are being tested here:
y=2x
y=x^2
y=1/x

It is hard to imagine y=2x, so for the sake of it, replace y=2x with y=x. Having all these graphs, you know that all these graphs intersect at (1,1)

Therefore, the values you want to consider for x must be:
0<x<1
and
x>1

When 0<x<1, you know that 1/x > x > x^2
When x>1, you know that x^2 > x > 1/x

This hints that when x is close to 1, 2x must be greater than x^2 because of steeper slope.

This is just a good way to know which point to pick when you want to test these conditions.

Cheers.
Manager
Joined: 30 Jan 2006
Posts: 64
Followers: 1

Kudos [?]: 5 [0], given: 0

avenger wrote:
OA is D.

Thanks

A.

The condition fails when x = 1...So i think the answer should be A (None)
Similar topics Replies Last post
Similar
Topics:
GMAT-Prep PS1 2 17 Jan 2009, 02:47
2 GMAT -Prep PS1 6 21 Dec 2008, 07:50
1 GMAT Set 1, Q 22 3 30 Mar 2008, 08:19
PS- GMAT Prep1 -2 2 26 Apr 2007, 12:39
1 DS, 1 PS from GmatPrep 2 28 Feb 2007, 03:52
Display posts from previous: Sort by