In the figure above, what is the value of x + y ?

Oldest

Best Reply

Author

Message

TAGS:

Manager

Joined: 02 Dec 2012

Posts: 178

Followers: 1

Kudos [?]: 7 [0], given: 0

In the figure above, what is the value of x + y ? [#permalink]

18 Dec 2012, 06:08

00:00

Difficulty:

20% (low)

Question Stats:

55% (01:29) correct

44% (00:32) wrong

based on 27 sessions

Attachment:

Triangles.png [ 7.26 KiB | Viewed 852 times ]

In the figure above, what is the value of x + y ?

(1) x = 70
(2) ABC and ADC are both isosceles triangles

[Reveal] Spoiler: OA

GMAT Club team member

Joined: 02 Sep 2009

Posts: 11611

Followers: 1801

Kudos [?]: 9597 [0], given: 829

Re: In the figure above, what is the value of x + y ? [#permalink]

18 Dec 2012, 06:19

In the figure above, what is the value of x + y ?

(1) x = 70.
(2) ABC and ADC are both isosceles triangles.

Even when we consider both statements together we don't know the placement of points D and B. For example consider the diagram below:

Attachment:

Triangles2.png [ 10.79 KiB | Viewed 792 times ]

As you can see we can have two different answers for x+y for two different placements of point D.

Answer: E.
_________________

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

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. NEW!!!

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. NEW!!!

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

Find out what's new at GMAT Club - latest features and updates

Manager

Joined: 26 Dec 2011

Posts: 119

Followers: 1

Kudos [?]: 6 [0], given: 17

Re: In the figure above, what is the value of x + y ? [#permalink]

27 Dec 2012, 02:30

Hi Bunuel, I see your point. However, what is the mistake when I follow this approach.

A: not sufficient
B: not sufficient

Taken together: <1+<2 = <3+<4 ==>since <2=<4; and therefore <1=<3

<1+<2+<3+<4+70 = 180
<2+<4=55

In triangle ADC <2+<4+y=180
from this we now know know y; we knew x.. so we get the answer.

Attachments

untitled.JPG [ 8.07 KiB | Viewed 670 times ]

GMAT Club team member

Joined: 02 Sep 2009

Posts: 11611

Followers: 1801

Kudos [?]: 9597 [0], given: 829

Re: In the figure above, what is the value of x + y ? [#permalink]

27 Dec 2012, 02:51

pavanpuneet wrote:

How did you get the red part above?
_________________

Manager

Joined: 26 Dec 2011

Posts: 119

Followers: 1

Kudos [?]: 6 [0], given: 17

Re: In the figure above, what is the value of x + y ? [#permalink]

27 Dec 2012, 02:57

Aah I see my mistake; i eqauted <1=<2 and <3=<4.

Spotted my error; thanks.

Intern

Joined: 13 Apr 2013

Posts: 16

Followers: 0

Kudos [?]: 0 [0], given: 3

In the figure above, what is the value of x + y ? [#permalink]

29 Apr 2013, 15:13

bhavinp wrote:

Answer is E

Here's a rough version of the image.

Statement 1 is insufficient.
We know angle x is 70, but we know nothing about the placement of point D. The lower the placement of point D the greater the angle y, so y could really be any number of values. Remember we can't assume anything about the placement of a point, unless we are explicitly told about the placement in the question.

Statement 2 is insufficient.
x and y could be any number of values. For instance x could be 50 degrees or 70 degrees. All we know is that the triangles are isosceles, but we know nothing about the angles.

Statements 1 and 2 together are insufficient.
From statement 1 we know x is 70 and that angles BAC and BCA are both 55. But again we know nothing about the placement of point D. Point D could be very close to B in which case y would be close to 70 degrees or point D could be close to the segment AC in which case y would be close to 180 degrees.

I hope that helps!
Bhavin

Maybe this is a silly question - I understood this problem but I have one issue with the answer explanation. Why do both angles have to be 55? Isoceles triangles must have at least two equivalent angles, right? Why couldn't the angles have been 70/70/40? Doesn't change the answer from E, but still im curious

Manager

Joined: 21 Jan 2010

Posts: 185

Followers: 0

Kudos [?]: 21 [0], given: 9

Re: In the figure above, what is the value of x + y ? [#permalink]

29 Apr 2013, 16:51

Well, this is more of analytical question. When i looked at this question , i tried to remember a formula that i could use but unfortunately couldn't fit anything but looking at the image i see a very generic image. Their is no way to determine x + y. As infinite number of such triangles can be drawn, which will satisfy the given constraints. Hence E wins.

GMAT Club team member

Joined: 02 Sep 2009

Posts: 11611

Followers: 1801

Kudos [?]: 9597 [0], given: 829

Re: In the figure above, what is the value of x + y ? [#permalink]

30 Apr 2013, 01:18

mokura wrote:

bhavinp wrote:

Answer is E

Here's a rough version of the image.

Merging similar topics.

As for your question: yes, ABC could be 70-70-40 triangle as well.
_________________

Magoosh GMAT Instructor

Joined: 28 Dec 2011

Posts: 842

Followers: 214

Kudos [?]: 585 [0], given: 14

Re: In the figure above, what is the value of x + y ? [#permalink]

01 May 2013, 10:13

Bunuel wrote:

Merging similar topics. As for your question: yes, ABC could be 70-70-40 triangle as well.

Bunuel and others,
I feel this question has a significant gap --- is the original diagram drawn to scale or not?

Of course, on the GMAT, we know "Figures are drawn as accurately as possible. Exceptions will be noted." I discuss this in a blog post.
http://magoosh.com/gmat/2012/gmat-trick ... -possible/
This is a crucial fact for students to keep in mind when interpreting GMAT diagrams.

IF this diagram is purporting to be drawn as accurate as possible, then it's an exceptionally poor diagram. That angle looks nothing like a 70 degree angle. If it's drawn to scale, though, we have to accept that the diagram is somewhat close to symmetrical, and therefore, the 70-70-40 triangle would not be possible.

IF the diagram is not drawn to scale, which I suspect was the intent of the author, that needs to be explicitly stated. Then, the 70-70-40 triangle would be possible. Any bilateral symmetry is out the window if it's not drawn to scale. Here's a scaled diagram of the figure with the 70-70-40 triangle.

Attachment:

isosceles triangles.JPG [ 25.57 KiB | Viewed 177 times ]

I believe, either way, the answer would be (E). Nevertheless, I think this is a crucial issue for students to consider while analyzing the possibilities for a given diagram on the GMAT.

What do others think?
Mike :-)

_________________

Mike McGarry
Magoosh Test Prep

Re: In the figure above, what is the value of x + y ? [#permalink] 01 May 2013, 10:13

		Similar topics	Author	Replies	Last post
Similar Topics:		What is the value of x + y in the figure above? (1) w = 95	tarek99	4	04 Aug 2008, 09:02
		Doc2.doc what is the value of x+y in the figure above? (1)	Baten80	2	08 Mar 2011, 14:16
	2	In the figure above, what is the value of x + y ?	mydreammba	4	28 Dec 2011, 07:48
	1	What is the value of x + y in the figure above?	Walkabout	1	26 Dec 2012, 05:18
	4	In the figure above, what is the value of x?	emmak	4	25 Mar 2013, 22:57

In the figure above, what is the value of x + y ?

Main navigation

GMAT Resources

Partners

MBA Resources

GMAT ® is a registered trademark of the Graduate Management Admission Council ® (GMAC ®). GMAT Club's website has not been reviewed or endorsed by GMAC.

GMAT Courses

Admissions Consulting

In the figure above, what is the value of x + y ?

In the figure above, what is the value of x + y ?

Main navigation

GMAT Resources

Partners

MBA Resources