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

It is currently 21 Aug 2018, 18:59

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, points A, B, C, D, and E lie on a line. A is

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
User avatar
Joined: 22 Feb 2006
Posts: 92
In the figure, points A, B, C, D, and E lie on a line. A is  [#permalink]

Show Tags

New post 28 Oct 2009, 15:59
2
9
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

49% (00:34) correct 51% (03:57) wrong based on 225 sessions

HideShow timer Statistics

Attachment:
Q2.jpg
Q2.jpg [ 6.76 KiB | Viewed 17396 times ]
In the figure, points A, B, C, D, and E lie on a line. A is on both circles, B is the center of the smaller circle, C is the center of the larger circle, D is on the smaller circle, and E is on the larger circle. What is the area of the region inside the larger circle and outside the smaller circle?

(1) AB = 3 and BC =2
(2) CD =1 and DE = 4

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
SVP
SVP
User avatar
Joined: 29 Aug 2007
Posts: 2419
Re: DS: Area between circles  [#permalink]

Show Tags

New post 28 Oct 2009, 18:41
TriColor wrote:
In the figure, points A, B, C, D, and E lie on a line. A is on both circles, B is the center of the smaller circle, C is the center of the larger circle, D is on the smaller circle, and E is on the larger circle. What is the area of the region inside the larger circle and outside the smaller circle?

(1) AB = 3 and BC =2
(2) CD =1 and DE = 4

--------
Please, explain your answer.


A.
From 1, we know the radii of the circles. SUFF..
From 2, we know the radius of only the large circle. NSF..

Update: Agree with D. Can get the d or r for small circle from 2.
_________________

Verbal: http://gmatclub.com/forum/new-to-the-verbal-forum-please-read-this-first-77546.html
Math: http://gmatclub.com/forum/new-to-the-math-forum-please-read-this-first-77764.html
Gmat: http://gmatclub.com/forum/everything-you-need-to-prepare-for-the-gmat-revised-77983.html


GT

Senior Manager
Senior Manager
User avatar
Joined: 18 Aug 2009
Posts: 293
Re: DS: Area between circles  [#permalink]

Show Tags

New post 28 Oct 2009, 20:28
2
I remember this Q from maybe OG12? and also remember getting this wrong :lol:

D

(A) as mentioned, both radius can be calculated. Area 25pi-9pi. Sufficient.
(B) CD=1, DE=4, CE, Big circle radius = 5
AC=5 (CA=CE), CD=1, AD -> Small circle diameter = 6, radius = 3. Area 25pi-9pi. Sufficient.
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 48110
Re: DS: Area between circles  [#permalink]

Show Tags

New post 29 Oct 2009, 01:39
I have some doubts about D. I got suspicious because I always beware of tricks when GMAT gives some drawings of figure. How do we know that this figure is drawn to scale?

In the figure we see that the point C (center of the bigger circle) is in the smaller circle, BUT it can be outside of it when the small circle diameter is less than the radius of the bigger.

In that case:

We are still able to answer the question with (1) as it doesn't change a thing for it: sufficient.

But for (2) CD = 1 and DE = 4 --> R=CD+DE=4+1=5, r=(2R-DE)/2=3 --> R=5, r=3.
OR
If C lies outside the smaller circle, CD = 1 and DE = 4. R=DE-CD=4-1=3, r=(R-CD)/2=(3-1)/2=1. R=3, r=1.
As we have different R and r, the area of the region inside the larger circle and outside the smaller circle would be different in each case. Not sufficient.

Answer: A.

Probably the most confusing thing here is that when we are dealing with (2) we already know R and r from (1) and it's more difficult to point out the trick, since you get the same R and r for (2) as well and thinking that "OK the same thing sufficient" forgetting to check whether C really lies inside the smaller circle or not.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

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?
Extra-hard Quant Tests with Brilliant Analytics

Director
Director
User avatar
Joined: 01 Apr 2008
Posts: 821
Name: Ronak Amin
Schools: IIM Lucknow (IPMX) - Class of 2014
Re: DS: Area between circles  [#permalink]

Show Tags

New post 29 Oct 2009, 01:51
Bunuel:

I am not sure about this...I guess the relative positioning of the points can be trusted even for diagrams. Only the size of line segments and angles can be something which "cant be drawn to scale". For example, if in this diagram we increase or decrease the scale, then also the relative position of points will be the same !
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 48110
Re: DS: Area between circles  [#permalink]

Show Tags

New post 29 Oct 2009, 02:05
Economist wrote:
Bunuel:

I am not sure about this...I guess the relative positioning of the points can be trusted even for diagrams. Only the size of line segments and angles can be something which "cant be drawn to scale". For example, if in this diagram we increase or decrease the scale, then also the relative position of points will be the same !


This would be interesting to find out: what should we "trust" in drawing and what not to. Let's wait for OA and OE. Plus maybe any GMAT tutor wants to bring the light to this problem.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

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?
Extra-hard Quant Tests with Brilliant Analytics

Manager
Manager
avatar
Joined: 15 Sep 2009
Posts: 118
Re: DS: Area between circles  [#permalink]

Show Tags

New post 29 Oct 2009, 05:02
statement 1:
==========
suff since we know the radius of both the circles.

statement 2:
==========
we can find the radius of larger circle. We can also find the diameter of the smaller circle,we can calculate the radius of the smaller circle.

I will choose option D
Senior Manager
Senior Manager
avatar
Joined: 18 Aug 2009
Posts: 287
Re: DS: Area between circles  [#permalink]

Show Tags

New post 29 Oct 2009, 06:31
@ Economist and Bunuel:

I agree with Economist here... Also OA is D. This problem is from OG 12: DS - Q.117
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 7780
Premium Member
Re: In the figure, points A, B, C, D, and E lie on a line. A is  [#permalink]

Show Tags

New post 10 Jul 2018, 21:05
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 Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Re: In the figure, points A, B, C, D, and E lie on a line. A is &nbs [#permalink] 10 Jul 2018, 21:05
Display posts from previous: Sort by

In the figure, points A, B, C, D, and E lie on a line. A is

  post reply Question banks Downloads My Bookmarks Reviews Important topics  

Events & Promotions

PREV
NEXT


GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| 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®.