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by ruplun » Sun Jun 26, 2011 2:19 am
Is x between 0 and 1?

(1) x^2 is less than x
(2) x^3 is positive
Source: — Data Sufficiency |

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by Frankenstein » Sun Jun 26, 2011 3:08 am
Hi,
From(1): x^2 < x
So, x^2 - x <0
So, x(x-1)<0
So, 0<x<1
Sufficient
From(2): x^3 is positive.
So, x is positive. Not sure whether x is less than 1 or not
Not sufficient

Hence, A
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by Sanjay2706 » Sun Jun 26, 2011 10:49 pm
Yes A is clearly the answer.
Square of no which is between 0 and 1 is always less than the no itself.
Statement 2 is insufficient.

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by mirantdon » Mon Jun 27, 2011 10:41 am
Imo A.
Well doesnt need an explanation

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by casperkamal » Tue Jun 28, 2011 8:28 am
Yep easy one

IMO... A
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by krishnasty » Tue Jun 28, 2011 7:56 pm
Clearly A..
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by edvhou812 » Tue Jun 28, 2011 9:25 pm
1) X^2<X. In this case X must be a positive fraction (Sufficient)
2) Only tells use that X^3 is positive. X could be any positive number. (Insufficient)

A.

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Re: x

by Brent@GMATPrepNow » Mon Jan 20, 2020 7:32 am
ruplun wrote:
Sun Jun 26, 2011 2:19 am
Is x between 0 and 1?

(1) x^2 is less than x
(2) x^3 is positive
Target question: Is x between 0 and 1 ?

Statement 1: x² is less than x
In other words, x² < x
We can apply some inequality rules here.
Since x² must be POSITIVE here, we can take x² < x and divide both sides by x²
We get: 1 < 1/x
Since 1/x is greater than 1, we can conclude that 1/x is positive, which means x is POSITIVE (i.e., x > 0)
Since x is POSITIVE, we can take 1 < 1/x and multiply both sides by x to get: x < 1
When we combine our two inequalities, we get 0 < x < 1
In other words, x IS between 0 and 1
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: x³ is positive
There are several values of x that satisfy statement 2. Here are two:
Case a: x = 1/2 (so, x³ = (1/2)³ = 1/8). In this case, x IS between 0 and 1
Case b: x = 2 (so, x³ = 2³ = 8). In this case, x is NOT between 0 and 1
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer: A
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