GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 15 Nov 2018, 11:45

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 in November
PrevNext
SuMoTuWeThFrSa
28293031123
45678910
11121314151617
18192021222324
2526272829301
Open Detailed Calendar
  • Free GMAT Strategy Webinar

     November 17, 2018

     November 17, 2018

     07:00 AM PST

     09:00 AM PST

    Nov. 17, 7 AM PST. Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.
  • GMATbuster's Weekly GMAT Quant Quiz # 9

     November 17, 2018

     November 17, 2018

     09:00 AM PST

     11:00 AM PST

    Join the Quiz Saturday November 17th, 9 AM PST. The Quiz will last approximately 2 hours. Make sure you are on time or you will be at a disadvantage.

If a, b, and c are integers. Is abc+ab+c an odd? 1) ac=odd 2) ab=odd

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

Hide Tags

Senior SC Moderator
User avatar
V
Joined: 14 Nov 2016
Posts: 1316
Location: Malaysia
GMAT ToolKit User Premium Member CAT Tests
If a, b, and c are integers. Is abc+ab+c an odd? 1) ac=odd 2) ab=odd  [#permalink]

Show Tags

New post 13 Mar 2017, 22:43
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

51% (01:57) correct 49% (02:16) wrong based on 144 sessions

HideShow timer Statistics

If a, b, and c are integers. Is abc+ab+c an odd?

1) ac=odd
2) ab=odd

_________________

"Be challenged at EVERY MOMENT."

“Strength doesn’t come from what you can do. It comes from overcoming the things you once thought you couldn’t.”

"Each stage of the journey is crucial to attaining new heights of knowledge."

Rules for posting in verbal forum | Please DO NOT post short answer in your post!

Advanced Search : https://gmatclub.com/forum/advanced-search/

Manager
Manager
avatar
S
Joined: 05 Apr 2014
Posts: 140
Location: India
Concentration: Economics, International Business
Schools: ISB '19, Fox"19
GMAT 1: 660 Q48 V33
GPA: 3
If a, b, and c are integers. Is abc+ab+c an odd? 1) ac=odd 2) ab=odd  [#permalink]

Show Tags

New post 13 Mar 2017, 23:06
D
1)ac is odd
2cases : b is even
Then even +even + odd -> odd
When b is odd then too the Sun is odd

2 ) ab is odd
cases when c is odd .
Then the entire Sun is odd
When c is even then too the sum is odd

Posted from my mobile device
Manager
Manager
avatar
S
Status: active
Joined: 25 Jan 2016
Posts: 139
Location: India
Concentration: Finance, Entrepreneurship
GPA: 4
WE: Web Development (Computer Software)
Re: If a, b, and c are integers. Is abc+ab+c an odd? 1) ac=odd 2) ab=odd  [#permalink]

Show Tags

New post 14 Mar 2017, 01:26
If a, b, and c are integers. Is abc+ab+c an odd?

1) ac=odd
2) ab=odd

ac=odd
i.e a and c both are odd
case 1 : when b is odd
abc=odd*odd=odd
ab=odd*odd
c=odd
so sum will also be odd

case 2: when b is even
abc=even
ab=even
c=odd
so sum will be odd
so Statement 1 is sufficient

same concept can be applied to statement 2 as well
so
Answer is D
Senior Manager
Senior Manager
User avatar
S
Status: Come! Fall in Love with Learning!
Joined: 05 Jan 2017
Posts: 490
Location: India
Premium Member
Re: If a, b, and c are integers. Is abc+ab+c an odd? 1) ac=odd 2) ab=odd  [#permalink]

Show Tags

New post 15 Mar 2017, 04:47
St 1: ac is odd. that means a is odd and c is odd. no idea about b. INSUFFICIENT
St 2: ab is odd. that means a is odd and b is odd. no idea about c. INSUFFICIENT

St 1 & St 2: a,b,c is odd. therefore abc is odd, ab is odd and c is odd
therefore abc +ab +c = odd +odd +odd = odd. ANSWER

Option C
_________________

GMAT Mentors
Image

SVP
SVP
User avatar
D
Joined: 26 Mar 2013
Posts: 1879
Reviews Badge CAT Tests
If a, b, and c are integers. Is abc+ab+c an odd? 1) ac=odd 2) ab=odd  [#permalink]

Show Tags

New post 15 Mar 2017, 17:32
If a, b, and c are integers. Is abc+ab+c an odd?

1) ac=odd

It means that both a & c are odd

Let a=c=1

abc+ab+c=b+b+1=2b+1=Even+ Odd=Odd

Sufficient

2) ab=odd

It means that both a & b are odd

Let a=b=1

abc+ab+c=c+1+c=2c+1=Even+odd=odd

Sufficient

Answer: D
Senior SC Moderator
User avatar
V
Joined: 14 Nov 2016
Posts: 1316
Location: Malaysia
GMAT ToolKit User Premium Member CAT Tests
Re: If a, b, and c are integers. Is abc+ab+c an odd? 1) ac=odd 2) ab=odd  [#permalink]

Show Tags

New post 27 Mar 2017, 17:19
1
ziyuen wrote:
If a, b, and c are integers. Is \(abc+ab+c\) an odd?

1) \(ac=odd\)
2) \(ab=odd\)


OFFICIAL SOLUTION



If you modify the original condition and the question, from abc+ab+c=odd?, ab(c+1)+c=odd?, you get the same result as c=odd?. This is because if c=odd, you get c+1=even, then ab(c+1)+c=ab(even)+odd=even+odd=odd, hence yes.

In the case of con 1), if ac=odd, the condition is yes and sufficient.

In the case of con 2), by the law of “CMT 4(B: if you get A or B too easily, consider D)”, when ab=odd,

① If c=odd, you get ab(c+1)+c=odd(odd+1)+odd=odd(even)+odd=odd, hence yes.

② If c=even, you get ab(c+1)+c=odd(even+1)=odd(odd)+even=odd, hence, in the case of ① and case of ②, it is always yes and sufficient. Therefore, the answer is D.
_________________

"Be challenged at EVERY MOMENT."

“Strength doesn’t come from what you can do. It comes from overcoming the things you once thought you couldn’t.”

"Each stage of the journey is crucial to attaining new heights of knowledge."

Rules for posting in verbal forum | Please DO NOT post short answer in your post!

Advanced Search : https://gmatclub.com/forum/advanced-search/

Intern
Intern
User avatar
B
Joined: 23 Jul 2015
Posts: 13
Location: India
GPA: 3.5
WE: Account Management (Accounting)
Re: If a, b, and c are integers. Is abc+ab+c an odd? 1) ac=odd 2) ab=odd  [#permalink]

Show Tags

New post 27 Mar 2017, 23:37
If a, b, and c are integers. Is abc+ab+c an odd?

1) ac=odd
2) ab=odd

1... odd*b + odd*b + odd ( as odd * odd = odd so a and c will e odds)
if b is odd then odd + odd + odd = odd and if b is even then, even + even + odd = odd sufficient
2... odd *c +odd + c
if c is odd then, odd + odd + odd = odd and if c is even then, even + odd + even = odd sufficient
hence, d
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 8772
Premium Member
Re: If a, b, and c are integers. Is abc+ab+c an odd? 1) ac=odd 2) ab=odd  [#permalink]

Show Tags

New post 12 Jul 2018, 04:25
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

GMAT Club Bot
Re: If a, b, and c are integers. Is abc+ab+c an odd? 1) ac=odd 2) ab=odd &nbs [#permalink] 12 Jul 2018, 04:25
Display posts from previous: Sort by

If a, b, and c are integers. Is abc+ab+c an odd? 1) ac=odd 2) ab=odd

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


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| 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®.