It is currently 20 Feb 2018, 07:45

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Is the product of a positive and a negative integer less

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

Hide Tags

Manager
Manager
avatar
Joined: 13 May 2010
Posts: 122
Is the product of a positive and a negative integer less [#permalink]

Show Tags

New post 24 Aug 2012, 00:14
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

84% (00:43) correct 16% (00:48) wrong based on 92 sessions

HideShow timer Statistics

Is the product of a positive and a negative integer less than -10?

(1) The positive integer is greater than 3
(2) The negative integer is less than -2

What is wrong with this solution -

Let x and y be the positive and negative integer,

Now a) x>3
b) y<-2 also means that -y>2

Since I can multiply inequalities if both sides are positive then -xy>6 which means that xy< -6 so I cannot conclusively determine if xy is less than -10 and I get answer E

With number testing maximum product is -12 Hence answer is C which is the correct answer. What did I do wrong with the above method?
[Reveal] Spoiler: OA

Last edited by Bunuel on 24 Aug 2012, 00:21, edited 1 time in total.
RENAMED THE TOPIC.
Director
Director
User avatar
Joined: 22 Mar 2011
Posts: 608
WE: Science (Education)
Re: Is the product of a positive and a negative integer less [#permalink]

Show Tags

New post 24 Aug 2012, 03:40
teal wrote:
Is the product of a positive and a negative integer less than -10?

(1) The positive integer is greater than 3
(2) The negative integer is less than -2

What is wrong with this solution -

Let x and y be the positive and negative integer,

Now a) x>3
b) y<-2 also means that -y>2

Since I can multiply inequalities if both sides are positive then -xy>6 which means that xy< -6 so I cannot conclusively determine if xy is less than -10 and I get answer E

With number testing maximum product is -12 Hence answer is C which is the correct answer. What did I do wrong with the above method?


You forgot that your numbers are integers. Therefore, \(x\geq{4}\) and \(y\leq-3\). From here, continue as you did above.
_________________

PhD in Applied Mathematics
Love GMAT Quant questions and running.

DS Forum Moderator
avatar
G
Joined: 21 Aug 2013
Posts: 786
Location: India
Premium Member CAT Tests
Re: Is the product of a positive and a negative integer less [#permalink]

Show Tags

New post 18 Jan 2018, 07:35
teal wrote:
Is the product of a positive and a negative integer less than -10?

(1) The positive integer is greater than 3
(2) The negative integer is less than -2

What is wrong with this solution -

Let x and y be the positive and negative integer,

Now a) x>3
b) y<-2 also means that -y>2

Since I can multiply inequalities if both sides are positive then -xy>6 which means that xy< -6 so I cannot conclusively determine if xy is less than -10 and I get answer E

With number testing maximum product is -12 Hence answer is C which is the correct answer. What did I do wrong with the above method?



So lets say the positive integer is 'x' and the negative integer is 'y'. We have to determine if x*y < -10

(1) x > 3. So the minimum value of x is 4 (has to be an integer). But nothing about y, so insufficient.

(2) y < -2. So maximum value of y is -3 (has to be an integer). But nothing about x, so insufficient.

Combining the two statements, if we take x = 4 and y = -3, then their product = 4*-3 = -12. For any other values of x & y satisfying the two statements, product will be less than -12 only. (eg, x=5, y=-3 gives us -15 and x=4, y=-4 gives us -16 and so on...)
So if product is less than -12, it will obviously be less than -10 also. (any number to the left of -12 will also be to the left of -10 on the number line). Sufficient.

Hence C answer
Re: Is the product of a positive and a negative integer less   [#permalink] 18 Jan 2018, 07:35
Display posts from previous: Sort by

Is the product of a positive and a negative integer less

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


GMAT Club MBA Forum Home| About| Terms and Conditions| 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®.