IMO A
xyz>0 gives us 4 case
1... x(+)y(+)z(+)...all positive or 2 negatives in remaining three cases below:
2....x(+)y(-)z(-)
3....x(-)y(-)z(+)
4....x(-)y(+)z(-)
1. y<0 so case 2 &3 above apply
(x)(y^2)(z^3).... case 2 give<0 & case 3 gives<0 again...sufficient
2. x>0 now case 1 & 2 apply
for (x)(y^2)(z^3)... case 1 is >0 while case 2 is <0 ...insufficient
ans:A
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
Variables signs problem
Source: Beat The GMAT — Data Sufficiency |
-
earth@work
- Master | Next Rank: 500 Posts
- Posts: 248
- Thanked: 13 times
Very good explanation.earth@work wrote:IMO A
xyz>0 gives us 4 case
1... x(+)y(+)z(+)...all positive or 2 negatives in remaining three cases below:
2....x(+)y(-)z(-)
3....x(-)y(-)z(+)
4....x(-)y(+)z(-)
1. y<0 so case 2 &3 above apply
(x)(y^2)(z^3).... case 2 give<0 & case 3 gives<0 again...sufficient
2. x>0 now case 1 & 2 apply
for (x)(y^2)(z^3)... case 1 is >0 while case 2 is <0 ...insufficient
ans:A
carpe diem!
(x)(y^2)(z^3)<0?jfranco23 wrote:If xyz>0, is (x)(y^2)(z^3)<0?
1. y<0
2. x>0
--> (xyz)(z^2)*y<0?
--> is y<0
question is asking is Y<0
Clearly A is sufficient
B is not sufficient.
q: xyz>0, is x(y^2)(z^3) < 0? Y/N
(i) y<0
=> x>0 & z<0 or x<0 & z>0
x>0 & z<0: y^2>0, z^3<0 => xy^2z^3<0. Yes
x<0 & z>0: y^2>0, z^3>0=> xy^2z^3<0. Yes
Suff.
[A] or [D]
(ii) x>0
=> y>0 & z<0 or y<0 & z>0
y>0 & z<0: => y^2>0, z^3<0 => xy^2z^3<0. Yes
y<0 & z>0: => y^2>0, z^3>0 => xy^2z^3>0. No
Insuff.
hence, [A]
(i) y<0
=> x>0 & z<0 or x<0 & z>0
x>0 & z<0: y^2>0, z^3<0 => xy^2z^3<0. Yes
x<0 & z>0: y^2>0, z^3>0=> xy^2z^3<0. Yes
Suff.
[A] or [D]
(ii) x>0
=> y>0 & z<0 or y<0 & z>0
y>0 & z<0: => y^2>0, z^3<0 => xy^2z^3<0. Yes
y<0 & z>0: => y^2>0, z^3>0 => xy^2z^3>0. No
Insuff.
hence, [A]
Want to Beat GMAT.
Always do what you're afraid to do. Whoooop GMAT
Always do what you're afraid to do. Whoooop GMAT
