Club Challenges -- Triangle Problem : Quant Question Archive [LOCKED]
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 24 Jan 2017, 06:40

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Club Challenges -- Triangle Problem

Author Message
Manager
Joined: 15 Nov 2007
Posts: 135
Followers: 1

Kudos [?]: 50 [0], given: 2

Club Challenges -- Triangle Problem [#permalink]

### Show Tags

03 Jan 2008, 21:57
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

If one of two parallel lines has 7 points on it and the other has 8, how many triangles can be drawn using the points?

* 168
* 196
* 316
* 364
* 455

You can take 2 points out of 8 on one line and combine them with one of the 7 points on the other line, or you can take 2 points from the other line and combine them with one of the 8 points on the original line. Algebraically:
7C_8^2+8C_7^2 = 364
Director
Joined: 12 Jul 2007
Posts: 862
Followers: 15

Kudos [?]: 286 [0], given: 0

Re: Club Challenges -- Triangle Problem [#permalink]

### Show Tags

04 Jan 2008, 06:45
7*8C2 + 8*7C2
7*28 + 8*21
196 + 168 = 364

Imagine these two parallel lines. To form a triangle we need to have 1 point on one of the lines and 2 points on the opposite line.

7*8C2 = 7 ways to choose 1 point multiplied by the number of ways to choose 2 points from the 8 points on the other line

8*7C2 = 8 ways to choose 1 point multiplied by the number of ways to choose 2 points from the 7 points on the other line

add these together and that's your total. This is a combinations problem.
Manager
Joined: 04 Jan 2008
Posts: 84
Followers: 1

Kudos [?]: 14 [0], given: 0

Re: Club Challenges -- Triangle Problem [#permalink]

### Show Tags

05 Jan 2008, 05:04
approach as a combination, you can take 2 points from one line and one from another. then add
7C2 X 8C1 + 8C2 X 7C1
Intern
Joined: 06 Jan 2008
Posts: 9
Followers: 0

Kudos [?]: 0 [0], given: 0

Re: Club Challenges -- Triangle Problem [#permalink]

### Show Tags

06 Jan 2008, 06:45
D) 364

7.8c2 + 8.7c2
Re: Club Challenges -- Triangle Problem   [#permalink] 06 Jan 2008, 06:45
Display posts from previous: Sort by