Last visit was: 19 Jul 2024, 22:20 It is currently 19 Jul 2024, 22:20

Close

GRE Prep 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 GRE 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
Verbal Expert
Joined: 18 Apr 2015
Posts: 29125
Own Kudos [?]: 34156 [4]
Given Kudos: 25516
Send PM
avatar
Manager
Manager
Joined: 29 Nov 2017
Posts: 190
Own Kudos [?]: 134 [0]
Given Kudos: 0
Location: United States
GRE 1: Q142 V146
WE:Information Technology (Computer Software)
Send PM
avatar
Manager
Manager
Joined: 27 Feb 2017
Posts: 188
Own Kudos [?]: 142 [0]
Given Kudos: 0
Send PM
avatar
Manager
Manager
Joined: 29 Nov 2017
Posts: 190
Own Kudos [?]: 134 [0]
Given Kudos: 0
Location: United States
GRE 1: Q142 V146
WE:Information Technology (Computer Software)
Send PM
Re: If A*B is the greatest common factor of A and B, A$B is defi [#permalink]
kruttikaaggarwal wrote:
Little confused here. Does ' * ' mean multiplication sigh here or just a symbol like ' $ '? And please explain the solution? Took me 5 mins and I guessed the answer



Yeah, right it took me too almost 5 mins to come up with the answer but the

sign * means --multiplication. $ sigh means LCM of output of A*B and the least common multiple of LCM of A and B.

Hope I have cleared your doubt :)
avatar
Manager
Manager
Joined: 26 Jan 2018
Posts: 189
Own Kudos [?]: 166 [0]
Given Kudos: 0
GRE 1: Q165 V156
Send PM
Re: If A*B is the greatest common factor of A and B, A$B is defi [#permalink]
1
* is not multiplication, it is a symbol which means the GCF of 2 numbers.
avatar
Manager
Manager
Joined: 27 Feb 2017
Posts: 188
Own Kudos [?]: 142 [0]
Given Kudos: 0
Send PM
Re: If A*B is the greatest common factor of A and B, A$B is defi [#permalink]
1
Okay, so I tried this question again. And from what I know, * is not multiplication. @IshanGRE, I am not sure how you got the LCM of 180 and 60 to be 60. You might wanna re-check that. This is how it will be done:
A=12 and B=15.
Step 1: A*B= 12*15=GCF of 12 and 15=3
Step 2: A$B=12$15= LCM of 12 and 15= 60
Step 3: A∩B=(A*B) $ (A$B)= 12∩15= (12*15) $ (12$15). This is basically asking for LCM of GCF and LCM of 12 and 15= 3 (step 1) $ 60 (step 2) = LCM of 3 and 60= 60

Moderators, please let me know if this is the right way. Also, my main question here is, on test how do we know whether its a symbol of a multiplication sign?
Verbal Expert
Joined: 18 Apr 2015
Posts: 29125
Own Kudos [?]: 34156 [0]
Given Kudos: 25516
Send PM
Re: If A*B is the greatest common factor of A and B, A$B is defi [#permalink]
2
Expert Reply
What is making this question challenging (to some extent, however, it is not the hardest question on the planet) is the wording of the question itself.

The same is when you are approaching a test such as GRE: it is tricky, NOT difficult.

Back to the question: always, always break it into chunks. Do not think for a moment to the goal (the question's solution) you have to reach but the way to go through. You will be there without believing you are already in your end zone.

Quote:
If A*B is the greatest common factor of A and B


This means that we do have two numbers and we do have the GCF of these. A*B is simply a representation of these numbers. We could call them X and Y or Tom and Jerry. The symbol * is impossible of being a multiplication.

Quote:
A$B is defined as the least common multiple of A and B


Is the same of above, only that here we do have the LCM

Quote:
and A∩B is defined as equal to (A*B) $ (A$B)


this actually means: the common area (the interception) between A and B. Our A is A*B and our B is A$B: GCF $ LCM where $ is just a symbol to show the LCF.
Actually, we have to find the GCF of A*B, the LCM of A$B and then the LCM of the two combined.

A= 12 and B = 15. The GCF of 12 and 15 is 3. The LCM of 12 and 15 is 60. The LCM of both (3 and 60) is 60. E is the answer.

is it not easy to look this way ?? :)

Ask for further assistance.

Regards
Target Test Prep Representative
Joined: 09 May 2016
Status:Head GRE Instructor
Affiliations: Target Test Prep
Posts: 183
Own Kudos [?]: 272 [0]
Given Kudos: 114
Location: United States
Send PM
Re: If A*B is the greatest common factor of A and B, A$B is defi [#permalink]
1
Expert Reply
Carcass wrote:
If A*B is the greatest common factor of A and B, A$B is defined as the least common multiple of A and B, and A∩B is defined as equal to (A*B) $ (A$B), then what is the value of 12∩15?

(A) 42
(B) 45
(C) 48
(D) 52
(E) 60


12&15 = (12?15) ~ (12~15)

12?15 = GCF(12, 15) = 3

12~15 = LCM(12, 15) = 60

Thus:

(12?15) ~ (12~15) = 3~60 = LCM(3, 60) = 60

Answer: E
User avatar
Director
Director
Joined: 22 Jun 2019
Posts: 521
Own Kudos [?]: 662 [0]
Given Kudos: 161
Send PM
Re: If A*B is the greatest common factor of A and B, A$B is defi [#permalink]
IshanGre wrote:
The question requires attention to details and this is what GRE loves to play us with(even in the RC questions)

So here we are given 12∩15 in the formula of (A*B) $ (A$B)

A*B = 12*15 =180
and A$B is the LCM of 12 and 15 is 60 NOW

180 $(LCM) 60 = 60 which is E


PLEASE BE CAREFULL------
your approach is not correct coz A*B = 12*15 =180 its' not correct. They mean here A*B is (A*B is the greatest common factor of A and B)
User avatar
Director
Director
Joined: 22 Jun 2019
Posts: 521
Own Kudos [?]: 662 [0]
Given Kudos: 161
Send PM
Re: If A*B is the greatest common factor of A and B, A$B is defi [#permalink]
Carcass wrote:
What is making this question challenging (to some extent, however, it is not the hardest question on the planet) is the wording of the question itself.

The same is when you are approaching a test such as GRE: it is tricky, NOT difficult.

Back to the question: always, always break it into chunks. Do not think for a moment to the goal (the question's solution) you have to reach but the way to go through. You will be there without believing you are already in your end zone.

Quote:
If A*B is the greatest common factor of A and B


This means that we do have two numbers and we do have the GCF of these. A*B is simply a representation of these numbers. We could call them X and Y or Tom and Jerry. The symbol * is impossible of being a multiplication.

Quote:
A$B is defined as the least common multiple of A and B


Is the same of above, only that here we do have the LCM

Quote:
and A∩B is defined as equal to (A*B) $ (A$B)


this actually means: the common area (the interception) between A and B. Our A is A*B and our B is A$B: GCF $ LCM where $ is just a symbol to show the LCF.
Actually, we have to find the GCF of A*B, the LCM of A$B and then the LCM of the two combined.

A= 12 and B = 15. The GCF of 12 and 15 is 3. The LCM of 12 and 15 is 60. The LCM of both (3 and 60) is 60. E is the answer.

is it not easy to look this way ?? :)

Ask for further assistance.

Regards


If A*B is the greatest common factor of A and B, A$B is defined as the least common multiple of A and B, and A∩B is defined as equal to (A*B) $ (A$B), then what is the value of 12∩15? Is this means, at last, we need the LCM? But as far as I remember 12∩15 this symbol means we need to take the GCM. This means the common only. Confused me it.
Moderator
Moderator
Joined: 02 Jan 2020
Status:GRE Quant Tutor
Posts: 1091
Own Kudos [?]: 904 [0]
Given Kudos: 9
Location: India
Concentration: General Management
Schools: XLRI Jamshedpur, India - Class of 2014
GMAT 1: 700 Q51 V31
GPA: 2.8
WE:Engineering (Computer Software)
Send PM
If A*B is the greatest common factor of A and B, A$B is defi [#permalink]
This questions is Based on LCM and GCD and Custom Characters

A∩B is defined as equal to (A*B) $ (A$B)

12∩15 = (12*15) $ (12$15) [Check out following video to know about Custom Character]

A*B is the greatest common factor of A and B

12*15 = GCD(12,15) = 3 (Check out this video to know about how to find GCD using multiple methods)

A$B is defined as the least common multiple of A and B

12$15 = LCM(12,15) = 3*4*5 = 60

(12*15) $ (12$15) = 3 $ 60 = LCM(3,60) = 60

So, Answer will be E
Hope it helps!

Check out following videos for Functions and Custom Characters and LCM and GCD





User avatar
GRE Prep Club Legend
GRE Prep Club Legend
Joined: 07 Jan 2021
Posts: 4665
Own Kudos [?]: 69 [0]
Given Kudos: 0
Send PM
Re: If A*B is the greatest common factor of A and B, A$B is defi [#permalink]
Hello from the GRE Prep Club BumpBot!

Thanks to another GRE Prep 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.
Prep Club for GRE Bot
[#permalink]
Moderators:
GRE Instructor
49 posts
GRE Forum Moderator
26 posts
Moderator
1091 posts
GRE Instructor
218 posts

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