It is currently 22 Sep 2017, 15:58

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Another tricky one

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
1 KUDOS received
CEO
CEO
User avatar
Joined: 17 May 2007
Posts: 2950

Kudos [?]: 655 [1], given: 210

Another tricky one [#permalink]

Show Tags

New post 16 Jun 2008, 21:00
1
This post received
KUDOS
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Another tricky one.
Attachments

gmatprep-ds2.jpg
gmatprep-ds2.jpg [ 76.16 KiB | Viewed 1458 times ]

Kudos [?]: 655 [1], given: 210

Senior Manager
Senior Manager
avatar
Joined: 26 Jan 2008
Posts: 263

Kudos [?]: 117 [0], given: 16

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 16 Jun 2008, 21:12
bsd_lover wrote:
Another tricky one.


I'll go with (B).

To solve it,
BCO = 40
OBC = BCO = 40
BOC = 180 - (BCO + OBC) = 100
ABO = 180 - BCO = 140
BAO = BOA (opposite angles to equal sides) = (180 - 140)/2 = 20
_________________

My GMAT debrief

Kudos [?]: 117 [0], given: 16

Senior Manager
Senior Manager
avatar
Joined: 26 Jan 2008
Posts: 263

Kudos [?]: 117 [0], given: 16

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 16 Jun 2008, 21:37
bsd_lover wrote:
B is not the OA.


Nice question. Should be (D)
If COD = 60, then OBC = OCB = 30, and the rest follows

+1
_________________

My GMAT debrief

Kudos [?]: 117 [0], given: 16

Senior Manager
Senior Manager
avatar
Joined: 26 Jan 2008
Posts: 263

Kudos [?]: 117 [0], given: 16

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 16 Jun 2008, 21:49
bsd_lover wrote:
incognito1 wrote:
bsd_lover wrote:
B is not the OA.


Nice question. Should be (D)
If COD = 60, then OBC = OCB = 30, and the rest follows <--- how did you arrive to this ????

+1


COD = OBC + OCB (exterior angle = sum of 2 opposite interior angles)
But since OB = OC (= radius), each equals half of COD = 30
_________________

My GMAT debrief

Kudos [?]: 117 [0], given: 16

CEO
CEO
User avatar
Joined: 17 May 2007
Posts: 2950

Kudos [?]: 655 [0], given: 210

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 16 Jun 2008, 21:58
COD doesn't look like an exterior angle of triangle COB. COX (as attached ) is the correct exterior angle.

incognito1 wrote:

COD = OBC + OCB (exterior angle = sum of 2 opposite interior angles)
But since OB = OC (= radius), each equals half of COD = 30

Attachments

cox.JPG
cox.JPG [ 10.06 KiB | Viewed 1387 times ]

Kudos [?]: 655 [0], given: 210

1 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 26 Jan 2008
Posts: 263

Kudos [?]: 117 [1], given: 16

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 16 Jun 2008, 22:14
1
This post received
KUDOS
bsd_lover wrote:
COD doesn't look like an exterior angle of triangle COB. COX (as attached ) is the correct exterior angle.

incognito1 wrote:

COD = OBC + OCB (exterior angle = sum of 2 opposite interior angles)
But since OB = OC (= radius), each equals half of COD = 30


Nice catch. Try 2 with Answer (D):

BAO = BOA
OBC = BAO + BOA
or, OBC = 2*BOA

OBC = OCB
so, OCB = 2*BOA

COD = BAO + OCB
or, 3*BAO = 60
=> BAO = 20 and OCB = OBC = 40, rest follows...
_________________

My GMAT debrief

Kudos [?]: 117 [1], given: 16

CEO
CEO
User avatar
Joined: 17 May 2007
Posts: 2950

Kudos [?]: 655 [0], given: 210

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 17 Jun 2008, 00:24
good discussion incognito +1.

Kudos [?]: 655 [0], given: 210

Senior Manager
Senior Manager
User avatar
Joined: 07 Jan 2008
Posts: 398

Kudos [?]: 281 [0], given: 0

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 17 Jun 2008, 04:11
We can not sure A,B, and C are in line. So C is the best.

Kudos [?]: 281 [0], given: 0

Intern
Intern
avatar
Joined: 23 May 2008
Posts: 1

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

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 17 Jun 2008, 07:33
IMO ans is C.

rephrasing the given info
BAO=x
OCB=a
OBC=b
COD=c
BOA=d

d+b+c=180
d+180-2a+c=180
d=2a-c

In triangle ABO
x+180-a+d=180
x-a+d=0
x=a-d
x=a-(2a-c)
x=c-a

Stmt (1) c=60
we are not sure about a
Stmt (2) a=40
we are not sure about c

Together we have what we are looking for.
This is little time consuming but let me know if this can be done in any faster way.

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

Manager
Manager
User avatar
Joined: 11 Apr 2008
Posts: 128

Kudos [?]: 58 [0], given: 0

Location: Chicago
Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 17 Jun 2008, 13:05
incognito1 wrote:
bsd_lover wrote:
B is not the OA.


Nice question. Should be (D)
If COD = 60, then OBC = OCB = 30, and the rest follows

+1


Can you explain the COD = 60, then OBC = OCB = 30 part
_________________

Factorials were someone's attempt to make math look exciting!!!

Kudos [?]: 58 [0], given: 0

Senior Manager
Senior Manager
avatar
Joined: 26 Jan 2008
Posts: 263

Kudos [?]: 117 [0], given: 16

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 17 Jun 2008, 13:38
brokerbevo wrote:
incognito1 wrote:
bsd_lover wrote:
B is not the OA.


Nice question. Should be (D)
If COD = 60, then OBC = OCB = 30, and the rest follows

+1


Can you explain the COD = 60, then OBC = OCB = 30 part


Actually, that is incorrect (though the answer was inadvertently correct), as bsd_lover pointed out. Refer my next post, I believe that should be correct.
_________________

My GMAT debrief

Kudos [?]: 117 [0], given: 16

Director
Director
avatar
Joined: 01 Jan 2008
Posts: 619

Kudos [?]: 195 [0], given: 1

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 17 Jun 2008, 13:45
beautiful problem! Easy but tricky.

Kudos [?]: 195 [0], given: 1

Current Student
avatar
Joined: 28 Dec 2004
Posts: 3354

Kudos [?]: 316 [0], given: 2

Location: New York City
Schools: Wharton'11 HBS'12
Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 17 Jun 2008, 15:44
me likes triangle..

guys any good source on beefing up my geometery? i struggle with coordinate and advance triangle type of problems..such as the one posted by BSD

Kudos [?]: 316 [0], given: 2

Senior Manager
Senior Manager
User avatar
Joined: 07 Jan 2008
Posts: 398

Kudos [?]: 281 [0], given: 0

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 17 Jun 2008, 21:46
I cast doubt on the OA. Hypothesis does not tell that A, B, C are in one line.

Image

Image

Kudos [?]: 281 [0], given: 0

Intern
Intern
avatar
Joined: 18 Jun 2008
Posts: 42

Kudos [?]: 9 [0], given: 0

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 19 Jun 2008, 10:14
lexis wrote:
I cast doubt on the OA. Hypothesis does not tell that A, B, C are in one line.

Image

Image


Damn good call. Without knowing if AC is a straight line you can't relate BAO to ABO to CBO to BCO... so if the link can't be made and one angle is not enough. But if you bring both pieces of information together you have what you need.

Kudos [?]: 9 [0], given: 0

Intern
Intern
avatar
Joined: 18 Jun 2008
Posts: 42

Kudos [?]: 9 [0], given: 0

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 19 Jun 2008, 10:33
To figure out the problem you need Y and X to find Z : Z = 2Y - X. Therefore you need both statements together. Hopefully the picture makes it easier to see.

Image

Image

Kudos [?]: 9 [0], given: 0

CEO
CEO
User avatar
Joined: 17 May 2007
Posts: 2950

Kudos [?]: 655 [0], given: 210

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 19 Jun 2008, 15:20
Lexis,
I'd go with what is obvious. Even though the line is not mentioned to be straight, I feel that its clear enough in the diagram.

lexis wrote:
BSD, Do you have any idea?

Kudos [?]: 655 [0], given: 210

Intern
Intern
avatar
Joined: 09 Jun 2008
Posts: 9

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

Re: gmatprep 2 Geometry DS [#permalink]

Show Tags

New post 20 Jun 2008, 00:15
COD=40
COA=140=COB+BOA=COB+BAO
IE: BAO=140-COB
NOW, COB=180-2*(CBO)
OR, COB=180-2*(180-ABO)
OR, COB=180-360+ABO=ABO-180=2*BAO-180
THEREFORE,
BAO=140-2*BAO-180
OR, BAO=40
THEREFORE, (D)

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

Re: gmatprep 2 Geometry DS   [#permalink] 20 Jun 2008, 00:15
Display posts from previous: Sort by

Another tricky one

  post reply Question banks Downloads My Bookmarks Reviews Important topics  


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

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.