NEW HERE? LEARN MORE
closeclose
Last visit was: 26 Apr 2024, 07:53 It is currently 26 Apr 2024, 07:53
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

If a and b are integers, is a + b = 12?

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
chetan2u
RC & DI Moderator
Joined: 02 Aug 2009
Status:Math and DI Expert
Posts: 11181
Own Kudos [?]: 31950 [4]
Given Kudos: 291
Send PM
Reviews Badge
If a and b are integers, is a + b = 12? [#permalink] New post   18 Oct 2019, 00:52
4
Bookmarks
Expert Reply
00:00
A
B
C
D
E

Difficulty:

75% (hard)

Question Stats:

40% (01:44) correct 60% (01:20) wrong based on 68 sessions
Hide Show timer Statistics
If a and b are integers, is a + b = 12?

(1) \(a-b=7\)
(2) \(\frac{a}{b}=8\)

Chetan's questions
ShowHide Answer
Official Answer
D
User avatar
L
Kinshook
GMAT Club Legend
GMAT Club Legend
Joined: 03 Jun 2019
Posts: 5344
Own Kudos [?]: 3965 [1]
Given Kudos: 160
Location: India
Schools: HBS '22 CBS '22 Wharton '22
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Send PM
Reviews Badge
Re: If a and b are integers, is a + b = 12? [#permalink] New post   Updated on: 20 Oct 2019, 22:49
1
Kudos
chetan2u wrote:
If a and b are integers, is a + b = 12?

(1) \(a-b=7\)
(2) \(\frac{a}{b}=8\)

New question!!...


Asked: If a and b are integers, is a + b = 12?

(1) \(a-b=7\)
a - b = 7; (a,b) = {(even, odd),(odd,even)}
a + b = even + odd = odd
12 = even
a + b \(\neq\) 12
SUFFICIENT

(2) \(\frac{a}{b}=8\)
a = 8b
a+b = 9b;
9b \(\neq\) 12; since b is an integer
SUFFICIENT

IMO D

Originally posted by Kinshook on 18 Oct 2019, 00:56.
Last edited by Kinshook on 20 Oct 2019, 22:49, edited 1 time in total.
User avatar
L
stne
SVP
SVP
Joined: 27 May 2012
Posts: 1680
Own Kudos [?]: 1424 [1]
Given Kudos: 632
Send PM
Re: If a and b are integers, is a + b = 12? [#permalink] New post   20 Oct 2019, 09:15
1
Kudos
chetan2u wrote:
If a and b are integers, is a + b = 12?

(1) \(a-b=7\)
(2) \(\frac{a}{b}=8\)

New question!!...


(1) \(a-b=7\)
Let \(a + b = 12\) and \(a-b = 7\) on solving we see that \(a\) and \(b\) are not integers, So it is not possible that \(a-b =7\) and \(a+b= 12\) both be true and \(a\)and \(b\) be integers. SUFF

(2) \(\frac{a}{b}=8\)
So question becomes is \(8b +b = 12\) or is \(9b= 12\) ? we know that \(b\) is an integer hence \(9b\) can never be equal to \(12\), SUFF

Ans - D
chetan2u, please can you show how statement 2 is NOT SUFF. IMO ans should be D.
User avatar
L
chetan2u
RC & DI Moderator
Joined: 02 Aug 2009
Status:Math and DI Expert
Posts: 11181
Own Kudos [?]: 31950 [0]
Given Kudos: 291
Send PM
Reviews Badge
Re: If a and b are integers, is a + b = 12? [#permalink] New post   20 Oct 2019, 09:45
Expert Reply
stne wrote:
chetan2u wrote:
If a and b are integers, is a + b = 12?

(1) \(a-b=7\)
(2) \(\frac{a}{b}=8\)

New question!!...


(1) \(a-b=7\)
Let \(a + b = 12\) and \(a-b = 7\) on solving we see that \(a\) and \(b\) are not integers, So it is not possible that \(a-b =7\) and \(a+b= 12\) both be true and \(a\)and \(b\) be integers. SUFF

(2) \(\frac{a}{b}=8\)
So question becomes is \(8b +b = 12\) or is \(9b= 12\) ? we know that \(b\) is an integer hence \(9b\) can never be equal to \(12\), SUFF

Ans - D
chetan2u, please can you show how statement 2 is NOT SUFF. IMO ans should be D.


Yes, it is D.
Edited. Kudos for the solution.
User avatar
L
chetan2u
RC & DI Moderator
Joined: 02 Aug 2009
Status:Math and DI Expert
Posts: 11181
Own Kudos [?]: 31950 [0]
Given Kudos: 291
Send PM
Reviews Badge
Re: If a and b are integers, is a + b = 12? [#permalink] New post   20 Oct 2019, 22:39
Expert Reply
chetan2u wrote:
If a and b are integers, is a + b = 12?

(1) \(a-b=7\)
(2) \(\frac{a}{b}=8\)

New question!!...



Now a and b are integers, so a+b will be EVEN only when either BOTH rare even or BOTH are odd..

(1) \(a-b=7\)
a-b will be ODD only when one is odd and the other is even, so a+b will also be ODD and hence \(a+b\neq{12}\)

(2) \(\frac{a}{b}=8\)
a=8b... so a+b=8b+b=9b, and \(9b\neq{12}\), as b is an integer

D
GMAT Club Bot
gmatclubot
Re: If a and b are integers, is a + b = 12? [#permalink]
20 Oct 2019, 22:39
Moderator:
Bunuel
Math Expert
92933 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions