GMAT Changed on April 16th - Read about the latest changes here

It is currently 24 Apr 2018, 22:05

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If positive integers a and b are both odd, which of the following must

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 44647
If positive integers a and b are both odd, which of the following must [#permalink]

Show Tags

New post 10 Dec 2016, 06:25
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

68% (00:44) correct 32% (00:40) wrong based on 217 sessions

HideShow timer Statistics

BSchool Forum Moderator
User avatar
D
Joined: 12 Aug 2015
Posts: 2585
GRE 1: 323 Q169 V154
GMAT ToolKit User Premium Member
Re: If positive integers a and b are both odd, which of the following must [#permalink]

Show Tags

New post 10 Dec 2016, 06:29
1 KUDOS received
Manager
Manager
avatar
B
Joined: 02 Nov 2013
Posts: 94
Location: India
Re: If positive integers a and b are both odd, which of the following must [#permalink]

Show Tags

New post 10 Dec 2016, 09:10
1
This post received
KUDOS
If positive integers a and b are both odd.
A. ab ----- Odd * Odd = Odd
B. a(ab)-- Odd * Odd * Odd = Odd
C. b – a – 1 -- Odd - Odd - 1 = Odd
D. (a + b)/2 -- Odd + Odd / 2 = Odd
E. a – b ---- Odd - Odd = Even in all the cases. Hence answer is E.
1 KUDOS received
Board of Directors
User avatar
G
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3400
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User Premium Member
Re: If positive integers a and b are both odd, which of the following must [#permalink]

Show Tags

New post 10 Dec 2016, 09:41
1
This post received
KUDOS
Bunuel wrote:
If positive integers a and b are both odd, which of the following must not be odd?

A. ab
B. a(ab)
C. b – a – 1
D. (a + b)/2
E. a – b


A. ODD * ODD = ODD

B. ODD(ODD*ODD) = ODD

C. ODD - ODD = EVEN - 1 = ODD

D. ODD + ODD = EVEN/2 = EVEN/ODD

E. ODD - ODD = EVEN

So, Correct answer will be (E)
_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Manager
Manager
avatar
S
Joined: 18 Oct 2016
Posts: 139
Location: India
WE: Engineering (Energy and Utilities)
Re: If positive integers a and b are both odd, which of the following must [#permalink]

Show Tags

New post 17 Apr 2017, 02:40
Option E

a & b are Odd integers. Odd: O, Even: E & Fraction: F.

A. ab = O*O = O
B. a(ab) = O(O*O) = O
C. b – a – 1 = O - O - 1 = E - 1 = O
D. (a + b)/2 = (O + O)/2 = E/2 = O
E. a – b = O - O = E
_________________

Press Kudos if you liked the post!

Rules for posting - PLEASE READ BEFORE YOU POST

Stern Thread Master
avatar
B
Status: Time to git gud
Joined: 17 Feb 2014
Posts: 41
Concentration: Strategy, General Management
WE: Operations (Commercial Banking)
GMAT ToolKit User
Re: If positive integers a and b are both odd, which of the following must [#permalink]

Show Tags

New post 23 Apr 2017, 00:18
A. o1*o2=o
B. o1(o1*o2)=o
C. o2-o1-1=o
D. (o1+o2)/2=o
E. o1-o2=e

Hence E
Intern
Intern
avatar
B
Joined: 30 Jul 2016
Posts: 6
Re: If positive integers a and b are both odd, which of the following must [#permalink]

Show Tags

New post 20 Jun 2017, 07:51
How come D is not the answer if we apply 3+5/2=4 , therefore even?

Bunuel wrote:
If positive integers a and b are both odd, which of the following must not be odd?

A. ab
B. a(ab)
C. b – a – 1
D. (a + b)/2
E. a – b
Board of Directors
User avatar
G
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3400
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User Premium Member
Re: If positive integers a and b are both odd, which of the following must [#permalink]

Show Tags

New post 20 Jun 2017, 08:02
Yoohanna wrote:
How come D is not the answer if we apply 3+5/2=4 , therefore even?

Bunuel wrote:
If positive integers a and b are both odd, which of the following must not be odd?

A. ab
B. a(ab)
C. b – a – 1
D. (a + b)/2
E. a – b


Good observation, thats why I mentioned the result of (D) may/may not be EVEN
Abhishek009 wrote:
D. ODD + ODD = EVEN/2 = EVEN/ODD


You have considered the numbers as 3 and 5 , see if I take the numbers as 1 and 5

\(\frac{(a + b)}{2} = \frac{6}{2} = 3 (ODD)\)

Thus, (D) may/may not be even...

_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Expert Post
EMPOWERgmat Instructor
User avatar
D
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 11513
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: 340 Q170 V170
Re: If positive integers a and b are both odd, which of the following must [#permalink]

Show Tags

New post 04 Dec 2017, 14:24
Hi All,

This question can be approached with Number Property rules. We're told that A and B are both ODD, POSITIVE INTEGERS. We're asked which of the following MUST NOT be odd.

Answer A: (A)(B) = (odd)(odd) = odd
Answer B: (A)(A)(B) = (odd)(odd)(odd) = odd
Answer C: B - A - 1 = (odd) - (odd) - (odd) = odd
Answer D: (A+ B)/2 = (odd + odd)/2 = (even)/2 = COULD be even (re: 4/2 = 2) OR odd (re: 6/2 = 3)
Answer E: A - B = (odd) - (odd) = EVEN

There's only one answer that can NEVER be odd.

Final Answer:
[Reveal] Spoiler:
E


GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free
  Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************

Expert Post
Target Test Prep Representative
User avatar
G
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 2464
Location: United States (CA)
Re: If positive integers a and b are both odd, which of the following must [#permalink]

Show Tags

New post 11 Jan 2018, 14:45
Bunuel wrote:
If positive integers a and b are both odd, which of the following must not be odd?

A. ab
B. a(ab)
C. b – a – 1
D. (a + b)/2
E. a – b


Since odd - odd = even, answer choice E, a - b is not odd.

Answer: E
_________________

Scott Woodbury-Stewart
Founder and CEO

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Re: If positive integers a and b are both odd, which of the following must   [#permalink] 11 Jan 2018, 14:45
Display posts from previous: Sort by

If positive integers a and b are both odd, which of the following must

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.