BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
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
Start Free 5-Day Trial Read 559 Reviews →

DS Problem

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 51
Joined: Sun Dec 19, 2010 1:49 pmFollowed by: 2 members
Thanked: 11 times
by jitsy » Thu Dec 23, 2010 12:42 pm
If a2 + b2 =13, what is the value of ab? (just to clarify, the 2s are squares)

(1) (a + b)2 = 25 (just to clarify, the 2 after a+b is square)

(2) a(ab3) = 108 (just to clarify, the 3 is cube)


Statement (1) ALONE is sufficient, but statement (2) ALONE is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) ALONE is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.



I got D since both can answer
But the test I took says the answer is A. Am I missing something? Doesn't B also help?

Please help.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Data Sufficiency |
Legendary Member
Posts: 759
Joined: Mon Apr 26, 2010 10:15 amFollowed by: 3 members
Thanked: 85 times

by clock60 » Thu Dec 23, 2010 1:05 pm
if i got the typing well
a^2*b^3=108, 108=3^3*2^2, so possible values for a and b are
2^2*3^3=108 with a*b=2*3=6 and also
(-2)^2*(3)^3=108 with a*b=(-2)*(3)=-6
looks like 2 st insufficient
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 51
Joined: Sun Dec 19, 2010 1:49 pmFollowed by: 2 members
Thanked: 11 times

by jitsy » Thu Dec 23, 2010 1:52 pm
My bad. Didn't consider the possibility of the negative 2 in the (B).

Thanks a lot. Appreciate it.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 52
Joined: Wed Aug 12, 2009 8:05 amFollowed by: 1 member
GMAT Score:650

by anuptvm » Thu Dec 23, 2010 4:42 pm
jitsy wrote:If a2 + b2 =13, what is the value of ab? (just to clarify, the 2s are squares)

(1) (a + b)2 = 25 (just to clarify, the 2 after a+b is square)

(2) a(ab3) = 108 (just to clarify, the 3 is cube)


Please help.
Statement 1 => a2 +2ab +b2 = 25 ; Given in the question that a2 +b2 =13 so we can find value of ab

Statement 2 => a2b3 = 2^2 . 3^3 which means a =2 ; b =3 OR a=-2 or b=3; so Stmt 2 insufficient
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 537
Joined: Fri Jan 22, 2010 10:06 pmFollowed by: 1 member
Thanked: 14 times

by frank1 » Fri Dec 24, 2010 2:37 am
Yup i think A should be answer
as there is no way of cancelling square and cube powers (one will be always more)
GMAT score is equally counted as your GPA and 78 clicks can change you life.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1