GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 16 Oct 2019, 22:31

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

In the figure above, does a = b?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Intern
Intern
avatar
Joined: 04 Feb 2014
Posts: 2
In the figure above, does a = b?  [#permalink]

Show Tags

New post Updated on: 28 Apr 2014, 02:45
6
00:00
A
B
C
D
E

Difficulty:

  65% (hard)

Question Stats:

49% (01:23) correct 51% (01:10) wrong based on 234 sessions

HideShow timer Statistics

Attachment:
gmat.jpg
gmat.jpg [ 3.86 KiB | Viewed 4470 times ]
In the figure above, does a = b?

(1) x = y

(2) c = x

Originally posted by systemm6665 on 27 Apr 2014, 07:52.
Last edited by Bunuel on 28 Apr 2014, 02:45, edited 1 time in total.
Renamed the topic and edited the question.
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58390
Re: In the figure above, does a = b?  [#permalink]

Show Tags

New post 28 Apr 2014, 02:54
2
Image
In the figure above, does a = b?

(1) x = y. This implies that x = y = 90° (straight line is 180°, hence each must be 90°) --> y = a = 90° (straight line is 180°, hence each must be 90°). So, the question asks whether a = b = 90°. Rotation of the lower line changes the measure of angle b, so there is no way to determine whether it's 90°. Not sufficient.

(2) c = x. Clearly insufficient.

(1)+(2) Since from (2) c = x, then from (1) c = x = y = 90°. Now, if c = 90°, then b = 90° too. Therefore a = b = 90°. Sufficient.

Answer: C.

Hope it's clear.

P.S. Please name the topics properly. Rule 3 here: rules-for-posting-please-read-this-before-posting-133935.html Thank you.
_________________
Intern
Intern
avatar
Joined: 04 Feb 2014
Posts: 2
Re: In the figure above, does a = b?  [#permalink]

Show Tags

New post 28 Apr 2014, 06:56
Thank you Bunuel. I will keep the topic name in mind for the next post. :)
Manager
Manager
avatar
Joined: 04 Apr 2013
Posts: 112
Re: In the figure above, does a = b?  [#permalink]

Show Tags

New post 29 Apr 2014, 04:55
Bunuel wrote:
Image
In the figure above, does a = b?

(1) x = y. This implies that x = y = 90° (straight line is 180°, hence each must be 90°) --> y = a = 90° (straight line is 180°, hence each must be 90°). So, the question asks whether a = b = 90°. Rotation of the lower line changes the measure of angle b, so there is no way to determine whether it's 90°. Not sufficient.

(2) c = x. Clearly insufficient.

(1)+(2) Since from (2) c = x, then from (1) c = x = y = 90°. Now, if c = 90°, then b = 90° too. Therefore a = b = 90°. Sufficient.

Answer: C.

Hope it's clear.

P.S. Please name the topics properly. Rule 3 here: rules-for-posting-please-read-this-before-posting-133935.html Thank you.



Bunuel,

Isnt B sufficient?

If C = x, then it will be the case where parallel lines bisected by the middle line. if parallel lines are bisected, isnt a= b?

Please let me know why I am wrong?
_________________
Maadhu

MGMAT1 - 540 ( Trying to improve )
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58390
Re: In the figure above, does a = b?  [#permalink]

Show Tags

New post 29 Apr 2014, 07:13
maaadhu wrote:
Bunuel wrote:
Image
In the figure above, does a = b?

(1) x = y. This implies that x = y = 90° (straight line is 180°, hence each must be 90°) --> y = a = 90° (straight line is 180°, hence each must be 90°). So, the question asks whether a = b = 90°. Rotation of the lower line changes the measure of angle b, so there is no way to determine whether it's 90°. Not sufficient.

(2) c = x. Clearly insufficient.

(1)+(2) Since from (2) c = x, then from (1) c = x = y = 90°. Now, if c = 90°, then b = 90° too. Therefore a = b = 90°. Sufficient.

Answer: C.

Hope it's clear.

P.S. Please name the topics properly. Rule 3 here: rules-for-posting-please-read-this-before-posting-133935.html Thank you.



Bunuel,

Isnt B sufficient?

If C = x, then it will be the case where parallel lines bisected by the middle line. if parallel lines are bisected, isnt a= b?

Please let me know why I am wrong?


We don't know whether the lines are parallel. What do you mean by "bisected"?
_________________
Intern
Intern
avatar
Joined: 08 Nov 2013
Posts: 37
GMAT 1: 730 Q50 V40
Re: In the figure above, does a = b?  [#permalink]

Show Tags

New post 07 Oct 2014, 05:15
1
Doesn't B imply that the two horizontal lines are parallel?
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58390
Re: In the figure above, does a = b?  [#permalink]

Show Tags

New post 07 Oct 2014, 07:31
Intern
Intern
avatar
Joined: 08 Nov 2013
Posts: 37
GMAT 1: 730 Q50 V40
Re: In the figure above, does a = b?  [#permalink]

Show Tags

New post 07 Oct 2014, 11:04
Bunuel wrote:
kamranjkhan wrote:
Image
Doesn't B imply that the two horizontal lines are parallel?


No. It implies that they are at the same angle to "vertical" line: since x = a and c = x, then c = a. Check an example below:
Attachment:
Untitled.png


Thanks! I got it horribly wrong.
Intern
Intern
avatar
Joined: 12 Oct 2014
Posts: 45
Location: India
Concentration: Finance, General Management
GMAT 1: 550 Q44 V21
WE: Analyst (Investment Banking)
Re: In the figure above, does a = b?  [#permalink]

Show Tags

New post 30 Jul 2015, 08:04
Bunuel wrote:
Image
In the figure above, does a = b?

(1) x = y. This implies that x = y = 90° (straight line is 180°, hence each must be 90°) --> y = a = 90° (straight line is 180°, hence each must be 90°). So, the question asks whether a = b = 90°. Rotation of the lower line changes the measure of angle b, so there is no way to determine whether it's 90°. Not sufficient.

(2) c = x. Clearly insufficient.

(1)+(2) Since from (2) c = x, then from (1) c = x = y = 90°. Now, if c = 90°, then b = 90° too. Therefore a = b = 90°. Sufficient.

Answer: C.

Hope it's clear.

P.S. Please name the topics properly. Rule 3 here: rules-for-posting-please-read-this-before-posting-133935.html Thank you.




Hi Bunuel,

One Q. If we consider only second statement i.e. c=x

This means, b= 180-x (straight lines, b+c=180)

Also, y= 180-x, this implies that a=x.

From here we can easily deduce that a and b are not equal.

Can you please tell me where exactly I have gone wrong ?

Thanks,
Gaurav
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58390
Re: In the figure above, does a = b?  [#permalink]

Show Tags

New post 30 Jul 2015, 08:13
GauravSolanky wrote:
Bunuel wrote:
Image
In the figure above, does a = b?

(1) x = y. This implies that x = y = 90° (straight line is 180°, hence each must be 90°) --> y = a = 90° (straight line is 180°, hence each must be 90°). So, the question asks whether a = b = 90°. Rotation of the lower line changes the measure of angle b, so there is no way to determine whether it's 90°. Not sufficient.

(2) c = x. Clearly insufficient.

(1)+(2) Since from (2) c = x, then from (1) c = x = y = 90°. Now, if c = 90°, then b = 90° too. Therefore a = b = 90°. Sufficient.

Answer: C.

Hope it's clear.

P.S. Please name the topics properly. Rule 3 here: rules-for-posting-please-read-this-before-posting-133935.html Thank you.




Hi Bunuel,

One Q. If we consider only second statement i.e. c=x

This means, b= 180-x (straight lines, b+c=180)

Also, y= 180-x, this implies that a=x.

From here we can easily deduce that a and b are not equal.

Can you please tell me where exactly I have gone wrong ?

Thanks,
Gaurav


Non-adjacent angles formed by the intersection of two straight lines are always equal, so a = x regardless whether c = x.

Also, I don't understand how you got that "we can easily deduce that a and b are not equal". Consider the simplest example to prove that a can be equal to b: a = b = c = x = y = 90 degrees.
_________________
CEO
CEO
User avatar
D
Status: GMATINSIGHT Tutor
Joined: 08 Jul 2010
Posts: 2977
Location: India
GMAT: INSIGHT
Schools: Darden '21
WE: Education (Education)
Reviews Badge
Re: In the figure above, does a = b?  [#permalink]

Show Tags

New post 30 Jul 2015, 10:42
systemm6665 wrote:
Attachment:
gmat.jpg
In the figure above, does a = b?

(1) x = y

(2) c = x


Statement 1: x = y
To establish the comparison between angles a and b we need to establish the relation between one of the angles {x, y, a} and {b, c}
First statement doesn't establish relationship between the two sets of angles. Hence,
NOT SUFFICIENT

Statement 2: c = x
Since, Angle x = Angle a [Vertically Opposite angles]
and c = x
therefore c = x = a
but, c+b = 180
i.e. a + b = 180 but a and b may or may NOT be equal.Hence,
NOT SUFFICIENT

Combining the two statements
x = y = c = a = 90 degrees [because x+y = 180]
and a + b = 180
i.e. b = 90 = a
SUFFICIENT

Answer: option C
_________________
Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION
VP
VP
User avatar
D
Joined: 05 Mar 2015
Posts: 1012
Reviews Badge
Re: In the figure above, does a = b?  [#permalink]

Show Tags

New post 07 Aug 2016, 12:35
systemm6665 wrote:
Attachment:
gmat.jpg
In the figure above, does a = b?

(1) x = y

(2) c = x



we can write x+y=180
y+a=180
x+y=y+a
x=a.....
Also
as C+B=180
and Y+A=180
means C+B=Y+A-----(a)

using both statements we can write Y=X=C
substituting in (a) we get A=B
suff..

Ans C
Manager
Manager
avatar
Joined: 07 Jul 2016
Posts: 74
GPA: 4
In the figure above, does a = b?  [#permalink]

Show Tags

New post 07 Aug 2016, 14:05
systemm6665 wrote:
Spoiler: :: Image
Image

In the figure above, does a = b?


\(a = x\)

\(y = 180 - x\)

\(b = 180 - c\)

\(\textbf{(1) } x = y\)

\(a = x = y = 90\)

We know nothing of the angle between \(b\) and \(c\) (the lines do not need to be parallel)

Insufficient

\(\textbf{(2) } c = x\)

\(b = 180 - c \implies b = 180 - a\)

\(a = 90 \implies b = a\\
a \neq 90 \implies b \neq a\)

Insufficient

\(b = 180 - a\\
a = 90\\
\therefore b = a\)

Sufficient

(C) both statements taken together are sufficient to answer the question, but neither statement alone is sufficient

_________________
Please press +1 Kudos if this post helps.
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 13204
Re: In the figure above, does a = b?  [#permalink]

Show Tags

New post 01 Feb 2019, 10:06
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Club Bot
Re: In the figure above, does a = b?   [#permalink] 01 Feb 2019, 10:06
Display posts from previous: Sort by

In the figure above, does a = b?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





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