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

It is currently 23 Jul 2014, 20:41

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

In the triangle above, what is the length of the side BC?

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Director
Director
User avatar
Joined: 03 Sep 2006
Posts: 893
Followers: 6

Kudos [?]: 88 [0], given: 33

In the triangle above, what is the length of the side BC? [#permalink] New post 10 Apr 2010, 03:50
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

60% (02:01) correct 40% (00:41) wrong based on 16 sessions
Attachment:
File comment: Figure
Triangle.PNG
Triangle.PNG [ 2.67 KiB | Viewed 1534 times ]

In the triangle above, what is the length of the side BC?

(1) Line segment AD has length 6
(2) x= 36

Can someone please explain the logic behind the explanation given in the official guide for the quantitative review-1st edition (question #117).

What I can't understand from the explanation is that it has been assumed that

angle ABD + angle DAB = 2x

will imply that ABD = DAB =x.

Why is the above true? Isn't it possible that ABD = 1.5x and DAB = 0.5x?

Why those two have to be equal?
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 18707
Followers: 3237

Kudos [?]: 22288 [0], given: 2611

Re: Quantitative Review #117 [#permalink] New post 10 Apr 2010, 04:30
Expert's post
LM wrote:
Can someone please explain the logic behind the explanation given in the official guide for the quantitative review-1st edition (question #117).

In the triangle above, what is the length of the side BC?

(1) Line segment AD has length 6

(2) x= 36

What I can't understand from the explanation is that it has been assumed that

angle ABD + angle DAB = 2x

will imply that ABD = DAB =x.

Why is the above true? Isn't it possible that ABD = 1.5x and DAB = 0.5x?

Why those two have to be equal?


We can no way assume that ABD=DAB=x, from ABD+DAB=2x. If we knew that either ABD or DAB equals to x, then the answer would be A. But in it's current form the answer should be E.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Director
Director
User avatar
Joined: 03 Sep 2006
Posts: 893
Followers: 6

Kudos [?]: 88 [0], given: 33

Re: Quantitative Review #117 [#permalink] New post 10 Apr 2010, 16:28
Bunuel wrote:
LM wrote:
Can someone please explain the logic behind the explanation given in the official guide for the quantitative review-1st edition (question #117).

In the triangle above, what is the length of the side BC?

(1) Line segment AD has length 6

(2) x= 36

What I can't understand from the explanation is that it has been assumed that

angle ABD + angle DAB = 2x

will imply that ABD = DAB =x.

Why is the above true? Isn't it possible that ABD = 1.5x and DAB = 0.5x?

Why those two have to be equal?


We can no way assume that ABD=DAB=x, from ABD+DAB=2x. If we knew that either ABD or DAB equals to x, then the answer would be A. But in it's current form the answer should be E.



This means that the Official Guide has the wrong answer. Official Guide gives the answer as "A", but I thought ( same as you!) that the answer should be"E".
whom shall we inform if the answer in the Official Guide is wrong?
Expert Post
CEO
CEO
User avatar
Joined: 17 Nov 2007
Posts: 3604
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Followers: 349

Kudos [?]: 1683 [0], given: 354

GMAT ToolKit User GMAT Tests User Premium Member
Re: Quantitative Review #117 [#permalink] New post 10 Apr 2010, 18:09
Expert's post
In my OG Quant 1 DAB=x.
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Director
Director
User avatar
Joined: 03 Sep 2006
Posts: 893
Followers: 6

Kudos [?]: 88 [0], given: 33

Re: Quantitative Review #117 [#permalink] New post 10 Apr 2010, 20:12
walker wrote:
In my OG Quant 1 DAB=x.


Walker,

I checked it again, and I believe they have not published two versions of Quant-I (review). :shock:

The official guide, page number 193, shows that BDC = 2x and BCD = 2x.

That's why I thought somehow the explanation or rather the answer given in the OG is incorrect. :shock:
Manager
Manager
avatar
Joined: 05 Mar 2010
Posts: 220
Followers: 1

Kudos [?]: 21 [0], given: 8

Re: Quantitative Review #117 [#permalink] New post 16 Apr 2010, 03:58
I think LM is right
Even in my quant, nothing is mentioned about angle DAB

explanation by OG - let angle DBA be y , so x + y = 2x (exterior angle) so x =y .........(but nowhere they mention that DAB is x)

Can official guide be wrong??? Surprise Surprise
_________________

Success is my Destiny

Re: Quantitative Review #117   [#permalink] 16 Apr 2010, 03:58
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic In triangle ABC above, what is the length of side BC? Bunuel 7 03 Mar 2014, 23:20
16 Experts publish their posts in the topic In triangle ABC above, what is the length of side BC? anilnandyala 13 21 Dec 2010, 07:17
In triangle ABC below, what is the length of side BC? 1, pinal2 4 01 Nov 2007, 09:40
In Triangle ABC, what is the length of side BC? 1) Line asaf 6 12 Jul 2007, 18:33
In triangle ABC above, what is the length of side BC? 1) netcaesar 4 14 Nov 2006, 11:10
Display posts from previous: Sort by

In the triangle above, what is the length of the side BC?

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

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®.