Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 04 May 2015, 04:48

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# If the symbol @ represents either addition or multiplication

Author Message
TAGS:
Manager
Joined: 17 Aug 2010
Posts: 54
Followers: 0

Kudos [?]: 19 [2] , given: 18

If the symbol @ represents either addition or multiplication [#permalink]  10 Nov 2010, 02:56
2
KUDOS
1
This post was
BOOKMARKED
00:00

Difficulty:

5% (low)

Question Stats:

84% (01:36) correct 16% (00:34) wrong based on 185 sessions
If the symbol @ represents either addition or multiplication, which operation does it represent?

(1) a@b=b@a for all numbers a and b
(2) a@(b–c)=(a@b)–(a@c) for all numbers a, b, and c
[Reveal] Spoiler: OA

_________________

I don't want kudos.. I want to see smile on your face if I am able to help you.. which is priceless.

Math Expert
Joined: 02 Sep 2009
Posts: 27205
Followers: 4225

Kudos [?]: 40976 [0], given: 5651

Expert's post
1
This post was
BOOKMARKED
zerotoinfinite2006 wrote:

[Reveal] Spoiler:
OA is "B", I am confused.

How come
a + ( b -c ) = (a + b) - (a + c) ?
and why not

a + b = b + a

If the symbol @ represents either addition or multiplication, which operation does it represent?

(1) a@b=b@a for all numbers a and b --> @ can be addition (a+b=b+a) as well as multiplication (a*b=b*a). Not sufficient.

(2) a@(b–c)=(a@b)–(a@c) for all numbers a, b, and c --> if @ represents addition we will have $$a@(b-c)=a+b-c$$ which is not equal to $$(a@b)-(a@c)=(a+b)-(a+c)=b-c$$, so @ must be multiplication. Sufficient. (Just to check: $$a@(b-c)=a*(b-c)=ab-ac$$ which is equal to $$(a@b)-(a@c)=ab-ac$$)

Similar problems:
symbol-problem-101741.html?hilit=symbol#p788840
ds-question-100955.html?hilit=symbol
just-800-level-question-99064.html?hilit=symbol

Hope it helps.
_________________
Math Expert
Joined: 02 Sep 2009
Posts: 27205
Followers: 4225

Kudos [?]: 40976 [0], given: 5651

Re: If the symbol @ represents either addition or multiplication [#permalink]  21 Jun 2013, 01:50
Expert's post
Bumping for review and further discussion*. Get a kudos point for an alternative solution!

*New project from GMAT Club!!! Check HERE

All DS Functions and Custom Characters questions: search.php?search_id=tag&tag_id=40
All PS Functions and Custom Characters questions: search.php?search_id=tag&tag_id=61

_________________
Intern
Joined: 22 May 2013
Posts: 49
Concentration: General Management, Technology
GPA: 3.9
WE: Information Technology (Computer Software)
Followers: 0

Kudos [?]: 11 [1] , given: 10

Re: If the symbol @ represents either addition or multiplication [#permalink]  22 Jun 2013, 02:28
1
KUDOS
zerotoinfinite2006 wrote:
If the symbol @ represents either addition or multiplication, which operation does it represent?

(1) a@b=b@a for all numbers a and b
(2) a@(b–c)=(a@b)–(a@c) for all numbers a, b, and c

Question: what is the operation @ ?
@ = + or *

As soon as you look at the questions, you will be reminded of the number properties Commutative and Distributive.

statement 1:
(1) a@b=b@a
Commutative property =>valid for both, + as well as *, =>cant say, Not Suff
(2) a@(b–c)=(a@b)–(a@c)
Distributive property=> Always valid for * -> Sufficient

_________________

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 4766
Followers: 295

Kudos [?]: 52 [0], given: 0

Re: If the symbol @ represents either addition or multiplication [#permalink]  23 Mar 2015, 00:00
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.
_________________
Re: If the symbol @ represents either addition or multiplication   [#permalink] 23 Mar 2015, 00:00
Similar topics Replies Last post
Similar
Topics:
2 The symbol © represents one of the following operations: addition, sub 4 11 Jan 2015, 11:14
3 In the addition problem above, each of the symbols □, △, and ★ represe 4 22 Dec 2014, 08:04
If the symbol # represents either addition, subtraction 3 26 Sep 2010, 10:46
The operation* represents either addition, subtraction, or 8 26 Oct 2007, 22:29
The operation* represents either addition, subtraction, or 5 08 Oct 2006, 09:24
Display posts from previous: Sort by

# If the symbol @ represents either addition or multiplication

 Powered by phpBB © phpBB Group and phpBB SEO 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®.