Find all School-related info fast with the new School-Specific MBA Forum

It is currently 07 Jul 2015, 12:57

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

What is the ratio of the surface area of a cube to the surfa

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Director
Director
avatar
Status: Finally Done. Admitted in Kellogg for 2015 intake
Joined: 25 Jun 2011
Posts: 552
Location: United Kingdom
Concentration: International Business, Strategy
GMAT 1: 730 Q49 V40
GPA: 2.9
WE: Information Technology (Consulting)
Followers: 30

Kudos [?]: 1174 [0], given: 217

What is the ratio of the surface area of a cube to the surfa [#permalink] New post 12 Feb 2012, 20:33
2
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

63% (02:02) correct 37% (00:53) wrong based on 174 sessions
What is the ratio of the surface area of a cube to the surface area of a rectangular solid identical to the cube in all ways except that its length has been doubled?

A. 1/4
B. 3/8
C. 1/2
D. 3/5
E. 2
[Reveal] Spoiler: OA

_________________

Best Regards,
E.

MGMAT 1 --> 530
MGMAT 2--> 640
MGMAT 3 ---> 610
GMAT ==> 730

1 KUDOS received
Manager
Manager
avatar
Joined: 31 Jan 2012
Posts: 74
Followers: 2

Kudos [?]: 17 [1] , given: 2

Re: Surface area of a cube [#permalink] New post 12 Feb 2012, 20:41
1
This post received
KUDOS
Let X be the side of the cube. Therefore X^2*6= surface area.

the rectangle is the same other than length is 2X. The width and height are the same as the cube. 2*W*H+2*W*L+2*H*L= 2X^2+4X^2+4X^2= 10X^2.

6X^2/10X^2 = 3/5.

Answer = D
Expert Post
3 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 28352
Followers: 4486

Kudos [?]: 45469 [3] , given: 6762

Re: What is the ratio of the surface area of a cube to the [#permalink] New post 13 Feb 2012, 05:25
3
This post received
KUDOS
Expert's post
enigma123 wrote:
What is the ratio of the surface area of a cube to the surface area of a rectangular solid identical to the cube in all ways except that its length has been doubled?

A)¼
B)3/8
C)½
D)3/5
E)2

Any idea how to solve these guys?


30 second approach:
A cube has 6 faces, suppose each has an area of 1, so surface area of the cube will be 6;

A rectangular solid identical to the cube in all ways except that its length has been doubled is just complicated way of saying that the rectangular solid is built with two cubes, hence it has 4+4+2=10 faces of a little cube (just imagine to cubes put one on another) and thus the surface area of the rectangular solid will be 10;

Ratio: 6/10=3/5.

Answer: D.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

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; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

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?
25 extra-hard Quant Tests

GMAT Club Premium Membership - big benefits and savings

Intern
Intern
avatar
Joined: 16 Dec 2011
Posts: 49
GMAT Date: 04-23-2012
Followers: 0

Kudos [?]: 2 [0], given: 12

Re: What is the ratio of the surface area of a cube to the [#permalink] New post 23 Feb 2012, 05:57
surface area of Cube = 6sidesqr
surface area of rectangular soild = 2( lb + bh+ hl)
assume side of cube is X
its surface area is 6Xsqr
surface area of Recatngular solid is = 10Xsqr ( 2( 2Xsqr+Xsqr +2Xsqr))
take ratio of these two we will get 6/10 = 3/5
Answer D
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 28352
Followers: 4486

Kudos [?]: 45469 [0], given: 6762

Re: What is the ratio of the surface area of a cube to the [#permalink] New post 27 May 2013, 04:51
Expert's post
Manager
Manager
avatar
Joined: 09 May 2013
Posts: 57
Followers: 0

Kudos [?]: 10 [0], given: 12

Re: What is the ratio of the surface area of a cube to the [#permalink] New post 22 Jun 2013, 00:56
Bunuel wrote:
enigma123 wrote:
What is the ratio of the surface area of a cube to the surface area of a rectangular solid identical to the cube in all ways except that its length has been doubled?

A)¼
B)3/8
C)½
D)3/5
E)2

Any idea how to solve these guys?


30 second approach:
A cube has 6 faces, suppose each has an area of 1, so surface area of the cube will be 6;

A rectangular solid identical to the cube in all ways except that its length has been doubled is just complicated way of saying that the rectangular solid is built with two cubes, hence it has 4+4+2=10 faces of a little cube (just imagine to cubes put one on another) and thus the surface area of the rectangular solid will be 10;

Ratio: 6/10=3/5.

Answer: D.


why "4+4+2" if there are two cubes than it should be "4+4" = 8 faces
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 28352
Followers: 4486

Kudos [?]: 45469 [0], given: 6762

Re: What is the ratio of the surface area of a cube to the [#permalink] New post 22 Jun 2013, 02:31
Expert's post
WarriorGmat wrote:
Bunuel wrote:
enigma123 wrote:
What is the ratio of the surface area of a cube to the surface area of a rectangular solid identical to the cube in all ways except that its length has been doubled?

A)¼
B)3/8
C)½
D)3/5
E)2

Any idea how to solve these guys?


30 second approach:
A cube has 6 faces, suppose each has an area of 1, so surface area of the cube will be 6;

A rectangular solid identical to the cube in all ways except that its length has been doubled is just complicated way of saying that the rectangular solid is built with two cubes, hence it has 4+4+2=10 faces of a little cube (just imagine to cubes put one on another) and thus the surface area of the rectangular solid will be 10;

Ratio: 6/10=3/5.

Answer: D.


why "4+4+2" if there are two cubes than it should be "4+4" = 8 faces


Plus 2 faces on the top and bottom. Put two dice one on another and see how many faces will it have.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

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; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

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?
25 extra-hard Quant Tests

GMAT Club Premium Membership - big benefits and savings

Manager
Manager
avatar
Joined: 07 May 2013
Posts: 109
Followers: 0

Kudos [?]: 12 [0], given: 1

Re: What is the ratio of the surface area of a cube to the surfa [#permalink] New post 14 Nov 2013, 19:12
\(\frac{6S^2}{2(lb+bh+hl)}\)=\(\frac{6x^2}{2(2x^2+x^2+2x^2)}\)=\(\frac{6x^2}{10x^2}\)=\(\frac{3}{5}\)
Manager
Manager
avatar
Joined: 07 May 2013
Posts: 109
Followers: 0

Kudos [?]: 12 [0], given: 1

Re: What is the ratio of the surface area of a cube to the surfa [#permalink] New post 14 Nov 2013, 19:17
Do not get confused as to why I took x. Let side of the cube be x. He says length is doubled. So, l=2x. However, b and h remain unchanged. So, b=h=x.
1 KUDOS received
SVP
SVP
User avatar
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1859
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Followers: 23

Kudos [?]: 971 [1] , given: 193

Re: What is the ratio of the surface area of a cube to the surfa [#permalink] New post 27 Mar 2014, 01:09
1
This post received
KUDOS
Area of cube = \(a^2 + a^2 + a^2 + a^2 + a^2 + a^2 = 6 a^2\)

When one of the dimension is doubled, it has impact on 4 sides (rest 2 remains same)

Look at the diagram

Area of rectangular solid \(= a^2 + a^2 + 2 a^2 + 2 a^2 + 2 a^2 + 2 a^2 = 10 a^2\)

Ratio \(= \frac{6 a^2}{10 a^2} = \frac{3}{5}\)

Answer = D
Attachments

cub.jpg
cub.jpg [ 22.23 KiB | Viewed 2015 times ]


_________________

Kindly press "+1 Kudos" to appreciate :)

SVP
SVP
User avatar
Joined: 06 Sep 2013
Posts: 2046
Concentration: Finance
GMAT 1: 770 Q0 V
Followers: 26

Kudos [?]: 315 [0], given: 355

GMAT ToolKit User
Re: What is the ratio of the surface area of a cube to the surfa [#permalink] New post 31 Mar 2014, 07:35
Hi All,

Let's assume leg of cube is 1 then surface area will be 6(1)^2=6. Now, rectangular solid will be (2)(1)(1), The area of the solid 2(ab+ac+bc) where a=2, b=1 and c=1. Thus its surface area totals 2(5)=10. So then D, 6/10=3/5 is the surface area.

D is the correct answer

Is this clear?

Cheers!
J :-D

I'm back
Intern
Intern
avatar
Joined: 23 Dec 2014
Posts: 43
Followers: 0

Kudos [?]: 2 [0], given: 50

Re: What is the ratio of the surface area of a cube to the surfa [#permalink] New post 27 Jan 2015, 14:38
Assume the length is Y

Surface are of Cube= 6Y^2

As the length is doubled for rectangle , other remains same. That means, rectangle's width,and height is "Y" but it's length is "2Y" now.

Let's see the surface area of Rectangle

Length = 2Y
Width = Y
Height = Y

So,
Multiplying length with height, 2Y x Y = 2Y^2 . Since there are two sides then it will be multiplied by two. So it will be 4Y^2

Multiplying length with width, 2Yx Y = 2Y^2 .Now multiply with two and we get 4Y^2

Multiplying Width with height, Y x Y = Y^2 Now multiply with two and we get 2Y^2

After Adding them , 4Y^2+4Y^2+2Y^2 = 10Y^2

Now,
6y^2/10Y^2 = 3/5
_________________

Three Best Android Applications for Gmat Preparation

Expert Post
Veritas Prep GMAT Instructor
User avatar
Joined: 16 Oct 2010
Posts: 5682
Location: Pune, India
Followers: 1415

Kudos [?]: 7361 [0], given: 186

Re: What is the ratio of the surface area of a cube to the surfa [#permalink] New post 27 Jan 2015, 21:15
Expert's post
enigma123 wrote:
What is the ratio of the surface area of a cube to the surface area of a rectangular solid identical to the cube in all ways except that its length has been doubled?

A. 1/4
B. 3/8
C. 1/2
D. 3/5
E. 2


Another way to think about it:

Imagine the cube with 6 equal faces. The surface area will be 6s^2 (s is the length of the edge of the cube).
Now imagine pulling on one face of the cube to elongate it. Now you have 4 extra equal faces on the four sides. The extra surface area is 4s^2.

Ratio of surface area of cube:surface area of rectangular solid = 6:10 = 3:5

Answer (D)
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for $199

Veritas Prep Reviews

Re: What is the ratio of the surface area of a cube to the surfa   [#permalink] 27 Jan 2015, 21:15
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic What will be the percentage increase in the area of the cube JubtaGubar 6 21 Apr 2012, 01:07
2 Experts publish their posts in the topic The volume of a cube is V cubic yards, and its surface area greatchap 4 17 Jul 2010, 21:20
3 Experts publish their posts in the topic What is the ratio of the surface area of a cube to the surfa sondenso 3 03 Mar 2008, 23:26
What is the ratio of the surface area of a cube to the trahul4 6 12 Aug 2007, 04:18
A cube and a right cylinder have the same surface area. If kevincan 6 25 Sep 2006, 03:51
Display posts from previous: Sort by

What is the ratio of the surface area of a cube to the surfa

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

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®.