Find all School-related info fast with the new School-Specific MBA Forum

It is currently 27 Jul 2014, 22:32

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

How many isosceles triangles can be constructed so that the

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
GMAT Instructor
avatar
Joined: 04 Jul 2006
Posts: 1270
Location: Madrid
Followers: 23

Kudos [?]: 113 [0], given: 0

How many isosceles triangles can be constructed so that the [#permalink] New post 07 Jul 2006, 07:33
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
How many isosceles triangles can be constructed so that the length of each side is a member of the following set?

L={1,2,3,4,5,6,7}

(A) 32 (B) 34 (C) 38 (D) 42 (E) 49
Manager
Manager
avatar
Joined: 26 Jun 2006
Posts: 154
Followers: 1

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

 [#permalink] New post 07 Jul 2006, 09:14
It should be 7P2 minus number of "impossible" combinations, where the sum of 2 sides is less than the 3rd side.

For example, {1,1,3} is impossible triangle. But I counted 12 such impossible combinations, and 42- 12 = 30 is not anong the answers :(

What did I do wrong?
Senior Manager
Senior Manager
User avatar
Joined: 07 Jul 2005
Posts: 406
Location: Sunnyvale, CA
Followers: 2

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

GMAT Tests User
 [#permalink] New post 07 Jul 2006, 10:02
am getting 30 too.

(1.,1) -- no isosceles triangles possible
(2,2) -- third side can be {1,3} = 2
(3,3) -- {1,2, 4, 5} = 4
(4, 4) -- {1, 2, 3, 5, 6, 7} = 6
(5, 5) = 6
(6, 6) = 6
(7, 7) = 6
GMAT Instructor
avatar
Joined: 04 Jul 2006
Posts: 1270
Location: Madrid
Followers: 23

Kudos [?]: 113 [0], given: 0

 [#permalink] New post 07 Jul 2006, 10:16
Indeed, there are 30 tr¡angles. Sorry for any distress! Both methods above are great!
  [#permalink] 07 Jul 2006, 10:16
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic How many triangles can be inscribed in the heptagon pictured fozzzy 5 12 Jun 2013, 21:38
21 Experts publish their posts in the topic How many triangles with positive area can be drawn on the dungtd 20 29 Jul 2010, 19:09
How many 7 letter words can be constructed using 26 letters chillpill 9 12 Apr 2006, 19:09
Right triangle PQR is to be constructed in the XY plane so Priti 8 14 Aug 2005, 12:44
Right triangle PQR is to be constructed in the xy-plane so kdhong 1 03 Jan 2005, 21:34
Display posts from previous: Sort by

How many isosceles triangles can be constructed so that the

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

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®.