• NEW! FREE Beat The GMAT Quizzes
    NEW! FREE Beat The GMAT Quizzes
    NEW! FREE Beat The GMAT Quizzes
    Hundreds of Questions Highly Detailed Reporting Expert Explanations TAKE A FREE GMAT QUIZ
  • 7 CATs FREE!
    If you earn 100 Forum Points

    Engage in the Beat The GMAT forums to earn
    100 points for $49 worth of Veritas practice GMATs FREE

    Veritas Prep
    VERITAS PRACTICE GMAT EXAMS
    Earn 10 Points Per Post
    Earn 10 Points Per Thanks
    Earn 10 Points Per Upvote
    REDEEM NOW

DS

This topic has 1 expert reply and 4 member replies

DS

Post
In the XY-plane , the line K passes through the origin and through the point (a, b), where ab is not equal to zero. Is b positive?

a. The slope of line K is negative

b. a< b

  • +1 Upvote Post
  • Quote
  • Flag
Legendary Member
Joined
29 Dec 2009
Posted:
1460 messages
Followed by:
7 members
Upvotes:
135
Facebook Logo
Post
stmt1,

slope is negative.

So the point (a,b) are in either second quadrant(-a,b) or fourth quadrant(a,-b)

Insuff

stmt2,

a
No info abt signs of a and b.

Insuff

combining 1 and 2,

Since a
b is positive,

Suff

Pick C

_________________
--Anand--

  • +1 Upvote Post
  • Quote
  • Flag
Legendary Member
Joined
02 Aug 2010
Posted:
866 messages
Upvotes:
31
Target GMAT Score:
700+
Facebook Logo
Post
selango wrote:
stmt1,

slope is negative.

So the point (a,b) are in either second quadrant(-a,b) or fourth quadrant(a,-b)

Can you please this a bit further,

I was thinking that line is goes downwards when slope is negative, I did not know that it can not be in I and III Quadrant, Can you please tell why is that so,

_________________
Saurabh Goyal
talk_to_saurabh@yahoo.com
-------------------------


EveryBody Wants to Win But Nobody wants to prepare for Win.

  • +1 Upvote Post
  • Quote
  • Flag
Legendary Member
Joined
29 Dec 2009
Posted:
1460 messages
Followed by:
7 members
Upvotes:
135
Facebook Logo
Post
If the slope is negative,the line goes downwards.

So the points can be in second quadrant(-a,b) or fourth quadrant(a,-b).

If the slope is positive,the line goes upwards.

So the points can be in first quadrant(a,b) or third quadrant(-a,-b).

_________________
--Anand--

  • +1 Upvote Post
  • Quote
  • Flag
Legendary Member
Joined
02 Aug 2010
Posted:
866 messages
Upvotes:
31
Target GMAT Score:
700+
Facebook Logo
Post
selango wrote:
If the slope is negative,the line goes downwards.

So the points can be in second quadrant(-a,b) or fourth quadrant(a,-b).

If the slope is positive,the line goes upwards.

So the points can be in first quadrant(a,b) or third quadrant(-a,-b).
Is that rule is compulsory for any line or only those lines that are passing through the origin ,
Can you please explain why is that so??????????

_________________
Saurabh Goyal
talk_to_saurabh@yahoo.com
-------------------------


EveryBody Wants to Win But Nobody wants to prepare for Win.

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Post
danjuma wrote:
In the XY-plane , the line K passes through the origin and through the point (a, b), where ab is not equal to zero. Is b positive?

1. The slope of line K is negative
2. a< b
Target question: Is b (the y-coordinate of the point on the line) positive?

Given: Line k passes through the origin and through the point (a,b)

Statement 1: The slope of line k is negative
There are several lines and points that satisfy statement 1. Here are two:

Case a:

In this case, b (y-coordinate) is positive. So, the answer to the target question is YES, b is positive

Case b:

In this case, b (y-coordinate) is negative. So, the answer to the target question is NO, b is NOT positive

Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: a < b
There are several lines and points that satisfy statement 2. Here are two:

Case a:

In this case, b (y-coordinate) is positive. So, the answer to the target question is YES, b is positive

Case b:

In this case, b (y-coordinate) is negative. So, the answer to the target question is NO, b is NOT positive

Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined
Statement 1 tells us that the slope of line k is negative. This means line k passes through quadrants II and IV.

In quadrant II, a (the x-coordinate) is always negative, and b (the y-coordinate) is always positive
In quadrant IV, a (the x-coordinate) is always positive, and b (the y-coordinate) is always negative

Statement 2 tells us that a < b
This means that the point (a,b) must be in quadrant II (because, all points in quadrant IV are such that the x-coordinate (a) is greater than the y-coordinate (b)
If point (a,b) is in quadrant II, we can be certain that b (the y-coordinate) is positive
Since we can answer the target question with certainty, the combined statements are SUFFICIENT

Answer: C

Cheers,
Brent

_________________
Brent Hanneson – Creator of GMATPrepNow.com
Use my video course along with Beat The GMAT's free 60-Day Study Guide

Sign up for free Question of the Day emails
And check out all of these free resources

  • +1 Upvote Post
  • Quote
  • Flag
GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months!
  • Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • The Princeton Review
    FREE GMAT Exam
    Know how you'd score today for $0

    Available with Beat the GMAT members only code

    MORE DETAILS
    The Princeton Review
  • e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep

Top First Responders*

1 Ian Stewart 44 first replies
2 Brent@GMATPrepNow 34 first replies
3 Scott@TargetTestPrep 32 first replies
4 Jay@ManhattanReview 31 first replies
5 GMATGuruNY 18 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

Most Active Experts

1 image description Scott@TargetTestPrep

Target Test Prep

139 posts
2 image description Max@Math Revolution

Math Revolution

90 posts
3 image description Ian Stewart

GMATiX Teacher

53 posts
4 image description Brent@GMATPrepNow

GMAT Prep Now Teacher

51 posts
5 image description Jay@ManhattanReview

Manhattan Review

31 posts
See More Top Beat The GMAT Experts