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:

Re: Lines m and n lie in the xy-plane and intersect at the point (-2; 4). [#permalink]

Show Tags

05 Dec 2011, 08:35

1

This post was BOOKMARKED

I would go with D. We are already given one point at the point of intersection. Statement 1 gives us an extra point therefore we can determine which line is steeper. sufficient Statement 2 also gives us the same information. sufficient

Re: Lines m and n lie in the xy-plane and intersect at the point (-2; 4). [#permalink]

Show Tags

11 Dec 2011, 13:33

liftoff wrote:

I would go with D. We are already given one point at the point of intersection. Statement 1 gives us an extra point therefore we can determine which line is steeper. sufficient Statement 2 also gives us the same information. sufficient

I was thinking if determining which one is steeper is enough or not.

Per (1) The x-intercept of line m is greater than the x-intercept of line n.

so line m can have a slope of lets say -2. If line n also has a -ve slope then it will need to be 'flatter' than line m for its x intercept to be greater than that of line m. So its slope will need to be > -2 (for -ve slopes flatter line are closer to 0 that slopes of steeper lines). so in this case slope of line n can be something like -1. So slope of n > slope of m (-1>-2). however, if slope of m is lets say 2, slope of n can be -ve like -2 with a greater x intercept. This satisfies the condition 1, but slope of m> slope of n in this case (2>-2). Hence, (1) is insufficient.

Similarly we can prove for the y intercept in case of 2nd statement.

The 2 statements taken together, they should still be insufficient.

could someone pl explain ? i'm unable to understand answer.

ALGEBRAIC WAY: Lines m and n lie in the xy-plane and intersect at the point (-2; 4). Is the slope of line m less than the slope of line n?

Equation of a line in point intercept form is \(y=mx+b\), where: \(m\) is the slope of the line, \(b\) is the y-intercept of the line (the value of \(y\) for \(x=0\)), \(-\frac{b}{m}\) is the x-intercept of the line (the value of \(x\) for \(y=0\)). (Check Coordinate Geometry chapter of Math Book for more on this topic: math-coordinate-geometry-87652.html)

We are given two lines: \(y_m=mx+b\) and \(y_n=nx+c\). Now, as they intersect at the point (-2; 4) then: \(4=-2m+b\) and \(4=-2n+c\) (this point is common for both of the lines) --> \(b=4+2m\) and \(c=4+2n\).

Question: is \(m<n\)?

(1) The x-intercept of line m is greater than the x-intercept of line n --> \(-\frac{b}{m}>-\frac{c}{n}\) --> \(-\frac{4+2m}{m}>-\frac{4+2n}{n}\) --> \(\frac{1}{n}-\frac{1}{m}>0\) --> insufficient to answer whether \(m<n\): if \(n=2\) and \(m=-4\) then YES but if \(n=2\) and \(m=4\) then NO. Not sufficient.

(2) The y-intercept of line n is greater than the y-intercept of line m --> \(c>b\) --> \(4+2n>4+2m\) --> \(n>m\). Sufficient.

could someone pl explain ? i'm unable to understand answer.

GRAPHIC APPROACH: Lines m and n lie in the xy-plane and intersect at the point (-2; 4). Is the slope of line m less than the slope of line n?

(1) The x-intercept of line m is greater than the x-intercept of line n. Draw lines: Case A:

Attachment:

graph.png [ 8.32 KiB | Viewed 5522 times ]

Red lines represent possible position of line m and blue line possible position of line n. (You can see that x-intercept of red lines>x-intercept of blue line, so the condition in the statement is satisfied). In the first case, both slopes are positive and red line (m) is steeper than blue line (n) which means that slope of line m>slope of line n (a steeper incline indicates a higher slope absolute value).

Case B:

Attachment:

graph 2.png [ 8.56 KiB | Viewed 5520 times ]

In this case, the slope of n is positive ans the slope of m is negative, hence slope of line n>slope of line m.

Two different answers. Not sufficient.

(2) The y-intercept of line n is greater than the y-intercept of line m. Draw lines: Case A:

Attachment:

graph 3.png [ 8.28 KiB | Viewed 5521 times ]

In the first case, both slopes are positive and blue line (n) is steeper than red line (m) which means that slope of line n>slope of line m (a steeper incline indicates a higher slope absolute value).Sufficient.

Case B:

Attachment:

graph 4.png [ 7.92 KiB | Viewed 5513 times ]

In this case, both slopes are negative and red line (m) is steeper than blue line (m), so the slope of m is more negative than slope of n (|m|>|n| --> -m>-n --> n>m), which again means that slope of line n>slope of line m.Sufficient.

Re: Lines m and n lie in the xy-plane and intersect at the point (-2; 4). [#permalink]

Show Tags

05 Nov 2013, 14:46

Bunuel wrote:

Bumping for review and further discussion.

I have seen a lot of examples of this question, and every time it comes down to the Y intercept. Can we use this as a shortcut? can we make a generalization here?

Re: Lines m and n lie in the xy-plane and intersect at the point (-2; 4). [#permalink]

Show Tags

28 Dec 2013, 16:14

2

This post received KUDOS

1

This post was BOOKMARKED

ronr34 wrote:

Bunuel wrote:

Bumping for review and further discussion.

I have seen a lot of examples of this question, and every time it comes down to the Y intercept. Can we use this as a shortcut? can we make a generalization here?

Yes we can use something else other than the graph method, which I find a little bit difficult to follow on many cases.

Let's see we need to know if m>n or if m-n>0, 'm and 'n' being the slopes of the respective lines

We know that they intersect at point (-2,4)

Then we have Line m= y = mx + b ---> 4 = -2m +b Line n = y = nx+c---> 4=-2n+c

Both equal, -2n+c= -2m+b 2m-2n = b-c m-n = (b-c)/2

Now going back to the question.

Is b-c/2 > 0?

is b-c>0, is b-c?

Statement 1

We are given that -b/m>-c/n -bn>-cm

We can't tell whether b>c Insuff

Statement 2

This is exactly what we were looking for b>c

Sufficient

B stands

Hope its clear Cheers! J

YES YOU CAN

Last edited by jlgdr on 18 May 2014, 09:05, edited 1 time in total.

Re: Lines m and n lie in the xy-plane and intersect at the point (-2; 4). [#permalink]

Show Tags

20 May 2015, 03:43

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.
_________________

Equation of a line in point intercept form is \(y=mx+b\), where: \(m\) is the slope of the line, \(b\) is the y-intercept of the line (the value of \(y\) for \(x=0\)),\(-\frac{b}{m}\) is the x-intercept of the line (the value of \(x\) for \(y=0\)). (Check Coordinate Geometry chapter of Math Book for more on this topic: math-coordinate-geometry-87652.html)
_________________

Hey, guys, So, I’ve decided to run a contest in hopes of getting the word about the site out to as many applicants as possible this application season...

Whether you’re an entrepreneur, aspiring business leader, or you just think that you may want to learn more about business, the thought of getting your Masters in Business Administration...

Term 1 has begun. If you're confused, wondering what my post on the last 2 official weeks was, that was pre-term. What that means is that the school...