GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

It is currently 03 Aug 2020, 19:05

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

What is the maximum number of points that can be placed on a circular

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

Hide Tags

Find Similar Topics 
Manager
Manager
User avatar
P
Joined: 18 Jan 2018
Posts: 184
Location: India
Concentration: Operations, International Business
Schools: CBS '22, ISB'21, Ivey '22
GPA: 3.27
WE: Operations (Other)
What is the maximum number of points that can be placed on a circular  [#permalink]

Show Tags

New post 04 Jun 2020, 03:21
6
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

38% (01:49) correct 62% (01:51) wrong based on 61 sessions

HideShow timer Statistics

What is the maximum number of points that can be placed on a circular disk of radius 1 meter (some of the points could be placed on the bounding circle of the disk) such that no two points are at a distance of less than 1 meter from each other.


A)9

B)8

C)6

D)5

E)7

_________________
Believe!!
Most Helpful Expert Reply
GMAT Tutor
avatar
P
Joined: 24 Jun 2008
Posts: 2393
Re: What is the maximum number of points that can be placed on a circular  [#permalink]

Show Tags

New post 04 Jun 2020, 05:16
4
1
To fit in as many points as possible, we'll want them to be as close together as possible, so (if we can) we want to make the distance between points 1 meter. Along a diameter, we can place three points -- one at the center, and two on the circumference. If we have a point at the center, every other point will need to be on the circumference, to be 1 meter away from the center.

So now we want points around the circumference that are 1 meter apart, in a straight line. If you take two consecutive points around the circumference, if they're 1 meter apart, and the radius is 1 meter, you'd make an equilateral triangle by connecting the two circumference points and the center. So there will be a 60 degree angle at the center, and going around the circle, you'll be able to place 6 points around the circumference that are 1 meter apart in a straight line (since 6*60 = 360). Including the center, we have 7 points in total.
_________________
GMAT Tutor in Montreal

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com
General Discussion
Senior Manager
Senior Manager
avatar
S
Joined: 18 Dec 2017
Posts: 307
Re: What is the maximum number of points that can be placed on a circular  [#permalink]

Show Tags

New post 04 Jun 2020, 07:36
4
Circumference of the circle =2×3.14×1
= 6.28
So 6 points on the circle and one at center total 7
Option E is the answer

Posted from my mobile device
Intern
Intern
avatar
B
Joined: 22 Mar 2020
Posts: 24
What is the maximum number of points that can be placed on a circular  [#permalink]

Show Tags

New post 05 Jul 2020, 00:48
IanStewart wrote:
To fit in as many points as possible, we'll want them to be as close together as possible, so (if we can) we want to make the distance between points 1 meter. Along a diameter, we can place three points -- one at the center, and two on the circumference. If we have a point at the center, every other point will need to be on the circumference, to be 1 meter away from the center.

So now we want points around the circumference that are 1 meter apart, in a straight line. If you take two consecutive points around the circumference, if they're 1 meter apart, and the radius is 1 meter, you'd make an equilateral triangle by connecting the two circumference points and the center. So there will be a 60 degree angle at the center, and going around the circle, you'll be able to place 6 points around the circumference that are 1 meter apart in a straight line (since 6*60 = 360). Including the center, we have 7 points in total.


you can't put a point on the center of a disc as in the center there is simply a hole
LBS Moderator
User avatar
P
Joined: 30 Oct 2019
Posts: 507
Location: United Kingdom
Concentration: General Management, Technology
GPA: 4
CAT Tests
Re: What is the maximum number of points that can be placed on a circular  [#permalink]

Show Tags

New post 05 Jul 2020, 02:36
robinbjoern wrote:
IanStewart wrote:
To fit in as many points as possible, we'll want them to be as close together as possible, so (if we can) we want to make the distance between points 1 meter. Along a diameter, we can place three points -- one at the center, and two on the circumference. If we have a point at the center, every other point will need to be on the circumference, to be 1 meter away from the center.

So now we want points around the circumference that are 1 meter apart, in a straight line. If you take two consecutive points around the circumference, if they're 1 meter apart, and the radius is 1 meter, you'd make an equilateral triangle by connecting the two circumference points and the center. So there will be a 60 degree angle at the center, and going around the circle, you'll be able to place 6 points around the circumference that are 1 meter apart in a straight line (since 6*60 = 360). Including the center, we have 7 points in total.


you can't put a point on the center of a disc as in the center there is simply a hole

I don't know how to react to this.
LBS Moderator
User avatar
P
Joined: 30 Oct 2019
Posts: 507
Location: United Kingdom
Concentration: General Management, Technology
GPA: 4
CAT Tests
Re: What is the maximum number of points that can be placed on a circular  [#permalink]

Show Tags

New post 05 Jul 2020, 02:46
gurmukh wrote:
Circumference of the circle =2×3.14×1
= 6.28
So 6 points on the circle and one at center total 7
Option E is the answer

Posted from my mobile device

I don't think the argument (highlighted) is justified. The circumference is an arc, and you want them away 1 meter on a straight line. So in my opinion we cannot draw this conclusion. If we take IanStewart 's method above of drawing equilateral triangles, that makes much more mathematical sense. What do you think?
GMAT Club Bot
Re: What is the maximum number of points that can be placed on a circular   [#permalink] 05 Jul 2020, 02:46

What is the maximum number of points that can be placed on a circular

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





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