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.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

If @ represents one of the operations +, -, and x, is k@(l+m)=(k@l)+(k@m) for all numbers k, l,and m?

(1) k@1 is not equal to 1@k for some numbers k. @ is neither addition (as \(k+1=1+k\)) nor multiplication (as \(k*1=1*k\)), thus @ represents subtraction. Knowing that we can determine whether \(k-(l+m)=(k-l)+(k-m)\) for all numbers k, l,and m. Sufficient.

(2) @ represents subtraction. The same here. Sufficient.

Re: If @ represents one of the operations +, -, and x, is k@(l+m [#permalink]

Show Tags

16 Dec 2012, 11:04

Bunuel wrote:

If @ represents one of the operations +, -, and x, is k@(l+m)=(k@l)+(k@m) for all numbers k, l,and m?

(1) k@1 is not equal to 1@k for some numbers k. @ is neither addition (as \(k+1=1+k\)) nor multiplication (as \(k*1=1*k\)), thus @ represents subtraction. Knowing that we can determine whether \(k-(l+m)=(k-l)+(k-m)\) for all numbers k, l,and m. Sufficient.

(2) @ represents subtraction. The same here. Sufficient.

Answer: D.

Dear Bunnel, I would like to understand the above question first.. If we take the @ as subtraction from statement 1 and 2 then the equation stands as \(k-l-m=2k-l-m\), which is not equal in both the side.

I was wondering whether the question asks about the operation of the @ sign, which makes the equation of k@(l+m)=(k@l)+(k@m) okay from both end.

If @ represents one of the operations +, -, and x, is k@(l+m)=(k@l)+(k@m) for all numbers k, l,and m?

(1) k@1 is not equal to 1@k for some numbers k. @ is neither addition (as \(k+1=1+k\)) nor multiplication (as \(k*1=1*k\)), thus @ represents subtraction. Knowing that we can determine whether \(k-(l+m)=(k-l)+(k-m)\) for all numbers k, l,and m. Sufficient.

(2) @ represents subtraction. The same here. Sufficient.

Answer: D.

Dear Bunnel, I would like to understand the above question first.. If we take the @ as subtraction from statement 1 and 2 then the equation stands as \(k-l-m=2k-l-m\), which is not equal in both the side.

I was wondering whether the question asks about the operation of the @ sign, which makes the equation of k@(l+m)=(k@l)+(k@m) okay from both end.

Thanks

No, the question asks: "is k@(l+m)=(k@l)+(k@m) for ALL numbers k, l,and m", where @ represents one of the operations +, -, and x.
_________________

If we take k=l=m=0 & k=1, l=2, m=3, from statement 1 we will get both "yes" or "no". Similarly Statement 2 also gives the same result.

The question doesn't specify anything about k,l,m

Could you explain?

From (1) we got that @ is subtraction. So, the question becomes: is k-(l+m)=(k-l)+(k-m) for ALL NUMBERS k, l,and m? This equation holds if k=0. Therefore the equation does NOT hold true for ALL NUMBERS (it holds if k=0).

Re: If @ represents one of the operations +, -, and x, is k@(l+m [#permalink]

Show Tags

12 Oct 2013, 11:20

The way I approached this question was basically "is @ multiplication"?

That is the only symbol that will make the equation in the question stem equal.

The first statement tells us indeed that @ is not multiplication or even addition. The only other option is subtraction...so we have our answer and it is not multiplication. Sufficient.

The second statement tells us @ is subtraction. Ok so we know it is not multiplication. Sufficient.

Re: If @ represents one of the operations +, -, and x, is k@(l+m [#permalink]

Show Tags

16 Nov 2013, 20:37

The way i see the question, k o (l +m) = (k o l) + (k o m) is only true where o is x(multiplication) for o = + and o = -, it's not true.

1. k o 1 not equal to 1 o k. This statement is true only when o is subtraction (-). But we know that the above statement is valid only for multiplication. So this option is SUFFICIENT. 2. o represents subtraction . This statement is SUFFICIENT , as we know that the question is valid only for multiplication.

Re: If @ represents one of the operations +, -, and x, is k@(l+m [#permalink]

Show Tags

16 Nov 2013, 22:24

1

This post received KUDOS

If @ represents one of the operations +, -, and x, is k@(l+m)=(k@l)+(k@m) for all numbers k, l,and m?

(1) k@1 is not equal to 1@k for some numbers k. (2) @ represents subtraction.

The answer to this question could be a yes or a no. If we can somehow say for sure - yes or no, then we know the option is sufficient. 2) clearly says @ is subtractn. Therefore, the equation in the question is NOT true for all nos. k,l,m. SUFFICIENT.

1)k@1 != 1@k implies that @ s not x . This could be + since if k is neg, -k+1 is not equal to 1-(-k) This could be - since k-1 != 1-k. substituting in the question, for +: is k+(l+m)=(k+l) + (k+m). NO. for - : is k-(l-m)= (k-l) + (k-m) . NO.

There the equation is NOT true for all nos. SUFFICIENT.

Re: If @ represents one of the operations +, -, and x, is k@(l+m [#permalink]

Show Tags

27 Nov 2014, 00:08

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.
_________________

If represents one of the operations +, -, and x, is k(l+m [#permalink]

Show Tags

17 Aug 2015, 22:16

1

This post was BOOKMARKED

Hi Guys,

Please correct me if I'm wrong, but this seems to be a wrong answer for the below question -

Refer the attachment.

I think the answer should be E as the equation has to be true for all numbers x,y, and z. x,y and z considered non-zero give the answer as NO for a "subtraction" sign. x,y and z ,all considered zero give the answer as YES for the same "subtraction" sign.

Attachments

File comment: This is a question.

GMAT Test Prep Wrong Answer.PNG [ 99.24 KiB | Viewed 3982 times ]

Last edited by Engr2012 on 23 Aug 2015, 04:18, edited 2 times in total.

Re: If represents one of the operations +, -, and x, is k(l+m)=(kl)+(k [#permalink]

Show Tags

22 Aug 2015, 23:23

Hi nuttyaks,

This is a tricky question that troubles a lot of students.

Based on statement 1, the symbol {o} has to be equal to subtraction, because in the case of addition and multiplication the operation k{o}1 is equal to 1{o}k for all all numbers. So the conclusion from statement 1 is that the symbol stands for only subtraction.

Now if we go back to the original question in the main stem, which asks if Does k{o}(l+m) = (k{o}l) + (k{o}m) for all numbers k, l, and m? meaning is the answer to this question a definite Yes or No. If the {o} stands for subtraction then the condition k-{l+m} is not equal to (k-l) + (k-m) for all numbers. It may hold true for k=l=m=0, but we need to answer the question if it holds true for all possible values of k, l, and m, and the answer to that is a definite No, which makes it sufficient.

Please correct me if I'm wrong, but this seems to be a wrong answer for the below question -

Refer the attachment.

I think the answer should be E as the equation has to be true for all numbers x,y, and z. x,y and z considered non-zero give the answer as NO for a "subtraction" sign. x,y and z ,all considered zero give the answer as YES for the same "subtraction" sign.

Please follow the posting guidelines and choose the correct forum for your questions.

You must type in the question completely with answer choices provided. Do not post pictures in lieu of the question.

Re: If represents one of the operations +, -, and x, is k(l+m [#permalink]

Show Tags

08 Jul 2016, 01:31

Bunuel wrote:

If @ represents one of the operations +, -, and x, is k@(l+m)=(k@l)+(k@m) for all numbers k, l,and m?

(1) k@1 is not equal to 1@k for some numbers k. @ is neither addition (as \(k+1=1+k\)) nor multiplication (as \(k*1=1*k\)), thus @ represents subtraction. Knowing that we can determine whether \(k-(l+m)=(k-l)+(k-m)\) for all numbers k, l,and m. Sufficient.

(2) @ represents subtraction. The same here. Sufficient.

Answer: D.

From both statement 1 and statment 2 we will get K=0 that means that this k@(l+m)=(k@l)+(k@m) is not true for all numbers. How come D be the solution it should be E?
_________________

If @ represents one of the operations +, -, and x, is k@(l+m)=(k@l)+(k@m) for all numbers k, l,and m?

(1) k@1 is not equal to 1@k for some numbers k. @ is neither addition (as \(k+1=1+k\)) nor multiplication (as \(k*1=1*k\)), thus @ represents subtraction. Knowing that we can determine whether \(k-(l+m)=(k-l)+(k-m)\) for all numbers k, l,and m. Sufficient.

(2) @ represents subtraction. The same here. Sufficient.

Answer: D.

From both statement 1 and statment 2 we will get K=0 that means that this k@(l+m)=(k@l)+(k@m) is not true for all numbers. How come D be the solution it should be E?

Happy New Year everyone! Before I get started on this post, and well, restarted on this blog in general, I wanted to mention something. For the past several months...

It’s quickly approaching two years since I last wrote anything on this blog. A lot has happened since then. When I last posted, I had just gotten back from...

Happy 2017! Here is another update, 7 months later. With this pace I might add only one more post before the end of the GSB! However, I promised that...

The words of John O’Donohue ring in my head every time I reflect on the transformative, euphoric, life-changing, demanding, emotional, and great year that 2016 was! The fourth to...