BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course
Redeem
Featured Course
Target Test Prep GMAT OnDemand
Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.
- 715+ score guarantee — highest in the industry (99th percentile)
- 52 chapters · 1,500+ lessons · 4,000+ practice questions
- 400 hours of video · 1,500+ instructor-led HD smartboard lessons
- 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
- 24/7 live support + weekly Zoom office hours with GMAT instructors
- TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
- 1,200+ flashcards + AI-powered study assistant & daily calendar
- OnDemand, LiveTeach & GMAT Bootcamp formats available
- Also: GRE, SAT Math & Executive Assessment courses
- MBA Admissions Consulting now available
- 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
- 200,000+ students served
- 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★
5.0
(559 reviews)
130-pt guarantee
$0 to start
then $127/mo
20q20
Source: Beat The GMAT — Data Sufficiency |
IMO E
St 1: n^3(1-x^3)<0
Now we can have two situations
If n is negative then x<1
Let n=-2, x=1/3
-8(1-1/9) = -64/9
But if n is positive x is an integer.
Let n=2 x=-3
8(1-9) = -64
In both these cases x could be positive or negative since x^2 is always positive----INSUFF
St 2. (x^2-1)<0
x^2<1
Again the only information we get from this statement is that x is a fraction. X could again be positive or negative. Try plugging in x=1/2 and x=-1/2 and the above condition will hold----INSUFF
Combining 1 & 2
(x^2-1) is negative
Hence (1-x^2) is positive.
And n is negative. But we still don't know whether x is positive or negative. We just know that x is a fraction less than 1. Try plugging in 1/2 and -1/2 as values of x and the above condition will hold
Hence the answer should be E
Whats the OA??
St 1: n^3(1-x^3)<0
Now we can have two situations
If n is negative then x<1
Let n=-2, x=1/3
-8(1-1/9) = -64/9
But if n is positive x is an integer.
Let n=2 x=-3
8(1-9) = -64
In both these cases x could be positive or negative since x^2 is always positive----INSUFF
St 2. (x^2-1)<0
x^2<1
Again the only information we get from this statement is that x is a fraction. X could again be positive or negative. Try plugging in x=1/2 and x=-1/2 and the above condition will hold----INSUFF
Combining 1 & 2
(x^2-1) is negative
Hence (1-x^2) is positive.
And n is negative. But we still don't know whether x is positive or negative. We just know that x is a fraction less than 1. Try plugging in 1/2 and -1/2 as values of x and the above condition will hold
Hence the answer should be E
Whats the OA??
from onestubbornp wrote:20. Is x negative ?
(1)n^3(1-x^2)<0
(2)x^2-1<0
either n -ve and (1-x^2) +ve(x is a fraction)...a
or n is positive and /x/>1............b........insuff
......
from 2
x^2<1.. x can be +ve or -ve??..........insuff
both
x is a fraction however we still dont know if it is +ve or -ve thus insuff
E is my answer
GMAT/MBA Expert
-
Ian Stewart
- GMAT Instructor
- Posts: 2623
- Location: Montreal
- Thanked: 1090 times
- GMAT Score:780
stubbornp, where are these questions from? Surely it's supposed to read 'x^3', not 'n^3'; otherwise the OA is wrong.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com
ianstewartgmat.com
ianstewartgmat.com
I think so..There has a discrepency in the stimulus or in answer.Source is 1000 DS..Ian Stewart wrote:stubbornp, where are these questions from? Surely it's supposed to read 'x^3', not 'n^3'; otherwise the OA is wrong.
