BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

★★★★★5.0559 reviews
Vote for Target Test Prep, Newsweek Readers’ Choice Awards 2026
NEWSWEEK READERS’ CHOICE 2026

BIG NEWS! Target Test Prep has been nominated, and they’d love your vote!

TTP has worked incredibly hard to build the best test prep experience possible, and winning Newsweek’s 2026 Readers’ Choice Award for Best Test Prep would mean a lot to them. If TTP has helped you, they’d be incredibly grateful for your vote. You can vote once each day through September 9.

Vote for TTP
GMATLiveTeach 7 seats left
Chris Peckover
NEXT LIVE COHORT

Oct 13 to Jan 7, 2027

with Chris Peckover

Schedule
Tue, Thu · 8:00 to 10:00 PM ET
Included
40 live hours + 6 months of GMAT OnDemand
  • Live instruction and real-time questions
  • Class recordings and assigned practice
View class & enroll
Limited cohort · enrollment openTarget Test Prep
EALiveTeach 5 seats left
Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

Schedule
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll
Limited cohort · enrollment openTarget Test Prep
GMATOnDemand Start anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 559 reviewsTarget Test Prep

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

line intersection??

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 45
Joined: Mon May 26, 2008 4:12 pm
by ch0719 » Sun Jan 04, 2009 10:26 pm
This is a question from MGMAT CAT online

My answer was D, but answer provided by MGMAT is A, and here is the explanation:

[spoiler]Lines are said to intersect if they share one or more points. In the graph, line segment QR connects points (1, 3) and (2, 2). The slope of a line is the change in y divided by the change in x, or rise/run. The slope of line segment QR is (3 – 2)/(1 – 2) = 1/-1 = -1.

(1) SUFFICIENT: The equation of line S is given in y = mx + b format, where m is the slope and b is the y-intercept. The slope of line S is therefore -1, the same as the slope of line segment QR. Line S and line segment QR are parallel, so they will not intersect unless line S passes through both Q and R, and thus the entire segment. To determine whether line S passes through QR, plug the coordinates of Q and R into the equation of line S. If they satisfy the equation, then QR lies on line S.

Point Q is (1, 3):
y = -x + 4 = -1 + 4 = 3
Point Q is on line S.

Point R is (2, 2):
y = -x + 4 = -2 + 4 = 2
Point R is on line S.

Line segment QR lies on line S, so they share many points. Therefore, the answer is "yes," Line S intersects line segment QR.

(2) INSUFFICIENT: Line S has the same slope as line segment QR, so they are parallel. They might intersect; for example, if Line S passes through points Q and R. But they might never intersect; for example, if Line S passes above or below line segment QR.

The correct answer is A. [/spoiler]


So here's my question: if Line S passes through points Q and R does it mean they intersect? Because imo for S to intersect with the line QR, line S must be able to devide line QR into two parts, thus if the slope of line S is same with the slope of QR then it means they will never intersect. I also remember that the theory goes two parallel lines never intersect.

Any other opinions? :shock:
Attachments
gmattemp.jpg
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Data Sufficiency |
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pmFollowed by: 11 members
Thanked: 331 times

by cramya » Sun Jan 04, 2009 10:57 pm
This one puzzles me also.

Stmt I and II pretty much gives the same info.

I would have choose D) also.

I am unable to understand how parallel lines will ever intersect. May be we are missing something.

The reason given for 1 could apply for 2 also since the slopes are being considered.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 1035
Joined: Wed Aug 27, 2008 10:56 pmFollowed by: 1 member
Thanked: 104 times

by scoobydooby » Sun Jan 04, 2009 11:01 pm
statement 1: says the lines are distinct and parallel.
statement 2: lines have same slope, we do not know if lines are distinct

have a confusion: are coincident lines said to intersect? i thought intersection meant cutting the line at a distinct point.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 2134
Joined: Mon Oct 20, 2008 11:26 pmFollowed by: 25 members
Thanked: 237 times
GMAT Score:730

by logitech » Mon Jan 05, 2009 2:43 am
The axiom in Euclidian Geometry is that parallel lines never intersect.

The axiom in non-Euclidian Geometry is that parallel lines intersect at infinity.

Statement 1) gives us the same line in question stem. So they overlap, is overlapping an intersection ? SURE ( You can also hear from a mathematician NO! )

Statement 2) IT might or MIGHT NOT - Slopes are the same but we don't know any other information about the line.
LGTCH
---------------------
"DON'T LET ANYONE STEAL YOUR DREAM!"
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 116
Joined: Fri Aug 29, 2008 10:22 am
Location: Mumbai,India
Thanked: 1 times

by bsandhyav » Mon Jan 05, 2009 3:46 am
cramya wrote:This one puzzles me also.

Stmt I and II pretty much gives the same info.

I would have choose D) also.

I am unable to understand how parallel lines will ever intersect. May be we are missing something.

The reason given for 1 could apply for 2 also since the slopes are being considered.


Def'n of intersecting lines: If a line has 1 or more points in common with another line the lines are said to be intersecting lines.


Coincident lines have all points in common ( i.e one or more than one). Hence they are considered to be intersecting lines.


St 1 : Since this statement gives the equation of the line S we can verify that the points on the segment coincide with that of line S. Hence the answer is YES. They are coincident lines


St2: This statement just mentions that the two slopes are the same(i.e -1).
This implies that the lines are either parllel (ie. non intersecting) or co-incident (which according to the def'n above are intersecting).
Hence we cannot say anything surely.

So St 1 alone is sufficient and st 2 is not IMO A

Hope this could make it clearer
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pmFollowed by: 11 members
Thanked: 331 times

by cramya » Mon Jan 05, 2009 8:51 pm
Thanks Sandhya!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 87
Joined: Tue Dec 23, 2008 11:06 pm
Thanked: 2 times

by rajataga » Sat Jan 10, 2009 5:55 am
ch017, wat you were talking about is called 'bisection' that is dividing the line into half.

Intersection is just a common point/s between 2 figures.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Senior | Next Rank: 100 Posts
Posts: 57
Joined: Wed Feb 17, 2010 6:15 pm
Location: MD
Thanked: 2 times

by GMAT680 » Fri Mar 12, 2010 4:20 pm
I think the explanation for statement 2 need to be. The lines are parallel and will never intersect. On the other hand, the given slope can be a slope of the given line. Hence, it overlaps (intersects).

That is the only justification to dispute choice. However, it disputes the golden rule of parallel lines will never cross each other.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 194
Joined: Thu Jan 14, 2010 5:18 am
Thanked: 2 times

by girish3131 » Sat Mar 13, 2010 12:13 am
Thanks for posting this ques....

a new maths concept learned after a long time......

GREAT DUDE....!!! keep posting such concept twisting ques.... Thanks once again....!!!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 75
Joined: Tue Jan 19, 2010 10:43 am

by sarthak » Tue Mar 16, 2010 2:32 am
New concept ..... hmmm interesting ... guys pls keep on posting such questions
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 758
Joined: Sat Aug 29, 2009 9:32 pmFollowed by: 2 members
Location: Bangalore,India
Thanked: 67 times

by sumanr84 » Sun Jul 18, 2010 9:38 am
Today I got this question in MGMAT CAT. Quite tricky, has anyone seen anything like that ever on GMAT ?

Does anyone knows how GMAT considers below defn..??

Def'n of intersecting lines: If a line has 1 or more points in common with another line the lines are said to be intersecting lines.


Coincident lines have all points in common ( i.e one or more than one). Hence they are considered to be intersecting lines.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1893
Joined: Sun May 30, 2010 11:48 pmFollowed by: 7 members
Thanked: 215 times

by kvcpk » Sun Jul 18, 2010 9:52 am
sumanr84 wrote:Today I got this question in MGMAT CAT. Quite tricky, has anyone seen anything like that ever on GMAT ?

Does anyone knows how GMAT considers below defn..??

Def'n of intersecting lines: If a line has 1 or more points in common with another line the lines are said to be intersecting lines.


Coincident lines have all points in common ( i.e one or more than one). Hence they are considered to be intersecting lines.
Very tricky indeed. I have no idea about how GMAT treats those definitions. But I believe the idea of the problem is correct.

Maths definition only says that two lines are said to be parallel when they are slopes are equal. This problem exploits that definition by making both the lines same. Need to give credit to the designer of this problem.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1