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

It is currently 19 Aug 2018, 04:35

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

If xy is not equal to 0, is xy = 70?

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

Hide Tags

Manager
Manager
avatar
Joined: 21 May 2011
Posts: 223
If xy is not equal to 0, is xy = 70?  [#permalink]

Show Tags

New post Updated on: 11 Jul 2013, 02:03
4
2
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

49% (01:06) correct 51% (01:14) wrong based on 112 sessions

HideShow timer Statistics

If xy is not equal to 0, is xy = 70?

(1) x > y

(2) x^2 = y^2

Originally posted by bschool83 on 07 Aug 2011, 10:36.
Last edited by Bunuel on 11 Jul 2013, 02:03, edited 1 time in total.
Added the OA.
Manager
Manager
User avatar
Joined: 14 Mar 2011
Posts: 195
Re: DS-700 level-inequality  [#permalink]

Show Tags

New post 07 Aug 2011, 11:01
1
bschool83 wrote:
If xy is not equal to 0, is xy = 70?

(1) x > y

(2) x^2 = y^2



Statement 1 is insufficient as values of x and y are not given

Statement 2 is insufficient too. if x^2 = Y^2 then |x| = |y| if x and y are equal to root 70 then xy will be 70. But if anything else then not.

Combining statement 1 and 2 we get sufficient answer that xy is not equal to 70. statement one tells that x is greater than y and statement 2 tells that x has same absolute value as y. so x = -Y. In that case xy must be negative.
so answer ( C )

If my answer is wrong then please correct it and please provide the OA and correct explanation.
Senior Manager
Senior Manager
avatar
Joined: 24 Mar 2011
Posts: 393
Location: Texas
Re: DS-700 level-inequality  [#permalink]

Show Tags

New post 07 Aug 2011, 11:19
great question. Agree with C.

B is not sufficient alone, since X, Y are not specified as integers.

also as per A and B, X can be 8.4 and Y can be -8.4. But then XY = -70
Manager
Manager
avatar
Joined: 16 May 2011
Posts: 196
Concentration: Finance, Real Estate
GMAT Date: 12-27-2011
WE: Law (Law)
GMAT ToolKit User
Re: DS-700 level-inequality  [#permalink]

Show Tags

New post 07 Aug 2011, 11:19
S1 x=70 y=1 yes. x=3 y=1 no
S2 X=ROOT 70 Y=ROOT 70 YES (x^2=y^2=70). X=9 Y=9 NO (x^2=y^2=81)

combined:
[x]=[y] and x>y means that x must be positive and y negative. Pos*Neg=Neg hence xy will never be 70. so C
Retired Moderator
User avatar
S
Joined: 18 Sep 2014
Posts: 1162
Location: India
GMAT ToolKit User Premium Member Reviews Badge
If xy is not equal to 0, is xy = 70?  [#permalink]

Show Tags

New post 04 Mar 2016, 05:01
1
If \(xy\neq{0}\), is \(xy = 70\)?

(1) \(x > y\)

(2) \(x^2 = y^2\)

OE

Attachment:
21oe.png
21oe.png [ 279.09 KiB | Viewed 1859 times ]

_________________

The only time you can lose is when you give up. Try hard and you will suceed.
Thanks = Kudos. Kudos are appreciated

http://gmatclub.com/forum/rules-for-posting-in-verbal-gmat-forum-134642.html
When you post a question Pls. Provide its source & TAG your questions
Avoid posting from unreliable sources.


My posts
http://gmatclub.com/forum/beauty-of-coordinate-geometry-213760.html#p1649924
http://gmatclub.com/forum/calling-all-march-april-gmat-takers-who-want-to-cross-213154.html
http://gmatclub.com/forum/possessive-pronouns-200496.html
http://gmatclub.com/forum/double-negatives-206717.html
http://gmatclub.com/forum/the-greatest-integer-function-223595.html#p1721773
https://gmatclub.com/forum/improve-reading-habit-233410.html#p1802265

Current Student
avatar
S
Joined: 20 Mar 2014
Posts: 2643
Concentration: Finance, Strategy
Schools: Kellogg '18 (M)
GMAT 1: 750 Q49 V44
GPA: 3.7
WE: Engineering (Aerospace and Defense)
GMAT ToolKit User Premium Member Reviews Badge
If xy is not equal to 0, is xy = 70?  [#permalink]

Show Tags

New post Updated on: 04 Mar 2016, 05:32
Nevernevergiveup wrote:
If \(xy\neq{0}\), is \(xy = 70\)?

(1) \(x > y\)

(2) \(x^2 = y^2\)


Given xy \neq 0, is xy=70?

Per statement 1, x>y ---> not sufficient.

Per statement 2, x^2=y^2 ----> yes to the question if \(x=y=\sqrt{70}\) but no if x=y=any other number!

Combining, if \(y=-\sqrt{70}\), \(x =\sqrt{70}\), and clearly you can see that \(x= \pm y\) ---> you will never get \(xy = 70\) (a positive value!). Hence C is the correct answer.

Hope this helps.

Originally posted by ENGRTOMBA2018 on 04 Mar 2016, 05:14.
Last edited by ENGRTOMBA2018 on 04 Mar 2016, 05:32, edited 2 times in total.
Edited the solution.
Manager
Manager
avatar
B
Joined: 28 May 2015
Posts: 53
Location: India
Concentration: Operations, Strategy
GMAT 1: 720 Q50 V38
GPA: 3
WE: Engineering (Manufacturing)
GMAT ToolKit User
Re: If xy is not equal to 0, is xy = 70?  [#permalink]

Show Tags

New post 06 Mar 2016, 02:49
Answer would be C
Because x>y is not sufficient.
X^2=Y^2=> X=±Y Not sufficient
But by combining both A and B, we can conclude X=-Y. So, xy≠positive number 70, xy will always be negative.
So C

Sent from my Mi 4i using Tapatalk
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6028
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Re: If xy is not equal to 0, is xy = 70?  [#permalink]

Show Tags

New post 06 Mar 2016, 04:02
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

If xy is not equal to 0, is xy = 70?

(1) x > y

(2) x^2 = y^2


In the original condition, there are 2 variables(x,y), which should match with the number of equations. So you need 2 equations. For 1) 1 equation, for 2) 1 equation, which is likely to make C the answer. When 1) & 2), x=y or x=-y -> x>y, which makes x=-y. In this case, xy<0 is derived and xy is not 70, which is no and sufficient.
Thus, C is the answer.


 For cases where we need 2 more equations, such as original conditions with “2 variables”, or “3 variables and 1 equation”, or “4 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 70% chance that C is the answer, while E has 25% chance. These two are the majority. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since C is most likely to be the answer using 1) and 2) separately according to DS definition (It saves us time). Obviously there may be cases where the answer is A, B, D or E.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Board of Directors
User avatar
P
Joined: 17 Jul 2014
Posts: 2717
Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30
GPA: 3.92
WE: General Management (Transportation)
GMAT ToolKit User Premium Member Reviews Badge
If xy is not equal to 0, is xy = 70?  [#permalink]

Show Tags

New post 15 Nov 2016, 07:40
bschool83 wrote:
If xy is not equal to 0, is xy = 70?

(1) x > y

(2) x^2 = y^2


what a tricky one...makes you feel that E is the answer...

1 alone is clearly not sufficient
2 alone says |x| = |y|. don't know anything. x can be+, y can be -, or vice versa, or x=y
different outcomes - not sufficient.

1+2
x>y
so x and y have different signs.
xy must be negative.

sufficient.

answer is C.
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 7759
Premium Member
Re: If xy is not equal to 0, is xy = 70?  [#permalink]

Show Tags

New post 06 Jul 2018, 06:34
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

Re: If xy is not equal to 0, is xy = 70? &nbs [#permalink] 06 Jul 2018, 06:34
Display posts from previous: Sort by

If xy is not equal to 0, is xy = 70?

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

Events & Promotions

PREV
NEXT


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®.