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

It is currently 13 Aug 2018, 23:39

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

The octahedron is an eight-faced geometric solid that can be thought o

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

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 47871
The octahedron is an eight-faced geometric solid that can be thought o  [#permalink]

Show Tags

New post 25 Feb 2015, 03:03
1
2
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

56% (00:57) correct 44% (00:59) wrong based on 93 sessions

HideShow timer Statistics

The octahedron is an eight-faced geometric solid that can be thought of as two square-based pyramids with the squares glued together. All eight faces of the octahedron are congruent equilateral triangles. Given that an edge is where the side of one equilateral triangles is attached to the side of another equilateral triangle, how many edges does the octahedron have?

(A) 8
(B) 10
(C) 12
(D) 16
(E) 18

Kudos for a correct solution.

_________________

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
User avatar
Status: Gmat Prep
Joined: 22 Jul 2011
Posts: 74
GMAT ToolKit User
Re: The octahedron is an eight-faced geometric solid that can be thought o  [#permalink]

Show Tags

New post 25 Feb 2015, 16:56
2
Octahedron has 12 sides answer is c

Image
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 6499
Re: The octahedron is an eight-faced geometric solid that can be thought o  [#permalink]

Show Tags

New post 25 Feb 2015, 22:51
1
Bunuel wrote:
The octahedron is an eight-faced geometric solid that can be thought of as two square-based pyramids with the squares glued together. All eight faces of the octahedron are congruent equilateral triangles. Given that an edge is where the side of one equilateral triangles is attached to the side of another equilateral triangle, how many edges does the octahedron have?

(A) 8
(B) 10
(C) 12
(D) 16
(E) 18

Kudos for a correct solution.



ans C... 12..
each pyramid has 4 edges between equilateral triangle and another four are created when two bases are joined..
total4*2+4=12..
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 47871
Re: The octahedron is an eight-faced geometric solid that can be thought o  [#permalink]

Show Tags

New post 02 Mar 2015, 05:32
Bunuel wrote:
The octahedron is an eight-faced geometric solid that can be thought of as two square-based pyramids with the squares glued together. All eight faces of the octahedron are congruent equilateral triangles. Given that an edge is where the side of one equilateral triangles is attached to the side of another equilateral triangle, how many edges does the octahedron have?

(A) 8
(B) 10
(C) 12
(D) 16
(E) 18

Kudos for a correct solution.


MAGOOSH OFFICIAL SOLUTION:

Again, we will use the analogy of Earth’s geography to orient us. (This, in and of itself, is a useful trick to remember.) When we glue together the two square faces, call that the “square equator” of the octagon. That’s a square, so obviously it have four edges. The pyramid above that goes up to a “north pole vertex”, and four edges run down that vertex to the corners of the “square equator,” so that’s four more. Similarly and symmetrically, the upside-down pyramid underneath comes to a point at the “south pole vertex”, with an additional four edges running from that vertex to the “square equator.” That’s four edges on the “square equator”, four more above, four more below, for a total of twelve edges on the octahedron.

Answer = C.
_________________

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

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 47871
Re: The octahedron is an eight-faced geometric solid that can be thought o  [#permalink]

Show Tags

New post 02 Mar 2015, 05:32
Bunuel wrote:
The octahedron is an eight-faced geometric solid that can be thought of as two square-based pyramids with the squares glued together. All eight faces of the octahedron are congruent equilateral triangles. Given that an edge is where the side of one equilateral triangles is attached to the side of another equilateral triangle, how many edges does the octahedron have?

(A) 8
(B) 10
(C) 12
(D) 16
(E) 18

Kudos for a correct solution.


Check other 3-D Geometry Questions in our Special Questions Directory.
_________________

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
G
Joined: 24 Nov 2015
Posts: 554
Location: United States (LA)
Reviews Badge
Re: The octahedron is an eight-faced geometric solid that can be thought o  [#permalink]

Show Tags

New post 31 Mar 2016, 14:34
if you can visualize the figure then answer comes out to be 12 in about 15 seconds
answer - C
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 7681
Premium Member
Re: The octahedron is an eight-faced geometric solid that can be thought o  [#permalink]

Show Tags

New post 04 Oct 2017, 10:28
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: The octahedron is an eight-faced geometric solid that can be thought o &nbs [#permalink] 04 Oct 2017, 10:28
Display posts from previous: Sort by

The octahedron is an eight-faced geometric solid that can be thought o

  new topic 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®.