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 →

Is the product of a and b odd?

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Data Sufficiency |
User avatar
Legendary Member
Posts: 1275
Joined: Thu Sep 21, 2006 11:13 pmFollowed by: 2 members
Location: Arabian Sea
Thanked: 125 times

by ajith » Sat Feb 20, 2010 3:22 am
gmatnmein2010 wrote:Is the product of a and b odd?

(1) a has exactly 2 factors.

(2) b = 2x + 1, where x is an integer.
1) Insufficient - It talks only about a

2) insufficient - it talks only about b

Combining

1) shows that a is a prime number (2,5...)
2) shows that b is an odd number

The product can be odd or even

Hence E
Always borrow money from a pessimist, he doesn't expect to be paid back.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1132
Joined: Mon Jul 20, 2009 3:38 amFollowed by: 6 members
Location: India
Thanked: 64 times
GMAT Score:760

by harsh.champ » Sat Feb 20, 2010 6:01 am
ajith wrote:
gmatnmein2010 wrote:Is the product of a and b odd?

(1) a has exactly 2 factors.

(2) b = 2x + 1, where x is an integer.
1) Insufficient - It talks only about a

2) insufficient - it talks only about b

Combining

1) shows that a is a prime number (2,5...)
2) shows that b is an odd number

The product can be odd or even

Hence E
I agree.
This question could have been more challenging if it was written that 2 is not a factor of a.
In that case,when we consider both the statements together,the product would always be an odd number.
This is because all prime no.s except 2 are odd.
Also,from statement 2 we know that b is an odd integer.
Odd x Odd =Odd
Hence,it could have been C.
That could have been a good trap.
It takes time and effort to explain, so if my comment helped you please press Thanks button :)



Just because something is hard doesn't mean you shouldn't try,it means you should just try harder.

"Keep Walking" - Johnny Walker :P
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1022
Joined: Mon Jul 20, 2009 11:49 pmFollowed by: 2 members
Location: Gandhinagar
Thanked: 41 times

by shashank.ism » Sat Feb 20, 2010 12:18 pm
gmatnmein2010 wrote:Is the product of a and b odd?

(1) a has exactly 2 factors.

(2) b = 2x + 1, where x is an integer.
St. 1 : a has exactly 2 factors. we know nothing about the factors. even we don't know about b ---------so insuff.
St.2 : b= 2x+1 and x is integer that is clearly and odd number ....since 2x is an even number as it has a factor 2 and when u add or subtract 1 from even number it gives an odd number
so b i an odd no.
but we know nothing about a --------so insuff..
combining : we know abt b is odd but we got no idea abt a ----- insuff.
Ans E
My Websites:
www.mba.webmaggu.com - India's social Network for MBA Aspirants

www.deal.webmaggu.com -India's online discount, coupon, free stuff informer.

www.dictionary.webmaggu.com - A compact free online dictionary with images.

Nothing is Impossible, even Impossible says I'm possible.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1