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

It is currently 28 Aug 2014, 19:54

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

M01 #11

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
1 KUDOS received
Manager
Manager
avatar
Joined: 12 Feb 2008
Posts: 182
Followers: 1

Kudos [?]: 33 [1] , given: 0

GMAT Tests User
M01 #11 [#permalink] New post 25 Sep 2008, 13:24
1
This post received
KUDOS
4
This post was
BOOKMARKED
If a cube with the length of the side of 4 cm is cut into smaller cubes with the length of the side of 1 cm, then what is the percentage increase in the surface area of the resulting cubes?

A. 4%
B. 166%
C. 266%
D. 300%
E. 400%

[Reveal] Spoiler: OA
D

Source: GMAT Club Tests - hardest GMAT questions


SOLUTION IS HERE: m01-70731-20.html#p1202018

Last edited by Bunuel on 12 Dec 2013, 01:33, edited 2 times in total.
Updated
Kaplan GMAT Prep Discount CodesKnewton GMAT Discount CodesManhattan GMAT Discount Codes
1 KUDOS received
CIO
CIO
avatar
Joined: 02 Oct 2007
Posts: 1218
Followers: 87

Kudos [?]: 656 [1] , given: 334

GMAT ToolKit User GMAT Tests User
Re: A 4 cm cube is cut into 1 cm cubes. [#permalink] New post 25 Sep 2008, 13:44
1
This post received
KUDOS
4 cm cube has 6 facets of 16 sq. cm each (96 sq. cm in all). After cutting the cube into 1 cm cubes we'll end up with 64 1 cm cubes. Each will have the surface area of 6 sq. cm. \frac{6*64}{6*16} = \frac{4}{1} = 400%. Therefore the increase in surface area must have been 300%. Did that without looking into the OE :lol: . Let's check now...
_________________

Welcome to GMAT Club! :)
Facebook TwitterGoogle+LinkedIn
Want to solve GMAT questions on the go? GMAT Club iPhone app will help.
Please read this before posting in GMAT Club Tests forum
Result correlation between real GMAT and GMAT Club Tests
Are GMAT Club Test sets ordered in any way?

Take 15 free tests with questions from GMAT Club, Knewton, Manhattan GMAT, and Veritas.

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Intern
Intern
avatar
Joined: 16 Jul 2008
Posts: 4
Followers: 1

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

m01-Q11.....explanation not clear...help please [#permalink] New post 02 Oct 2008, 11:53
A 4 cm cube is cut into 1 cm cubes. What is the percentage increase in the surface area after such cutting?

4%
166%
266%
300%
400%
The easiest way to solve this problem is to calculate the original surface area and then the final. The original area is 4*4*6. The new area is 1*1*6*4*4*4. So, the difference is 1:4. Therefore, the increase is 300%. You can also solve it logically, but that's more risky.

The correct answer is D.

I couldnt quite understand the explanation here...

The original area is 4*4*6 i agree, but the new area should be 1*1*6*4, why has 4 been multiplied 3 times. Could someone please explain. The question says that the original cube has been cut into 1cm cubes so there are 4 cubes in all now, and every cube will have 1cm side so the SA of every cube will be 1*1*6 and since we have four such cubes the Area of all these will be 6*4.

I am not sure what i am missing here.
4 KUDOS received
Intern
Intern
avatar
Joined: 10 Sep 2008
Posts: 38
Followers: 1

Kudos [?]: 22 [4] , given: 0

Re: m01-Q11.....explanation not clear...help please [#permalink] New post 03 Oct 2008, 09:10
4
This post received
KUDOS
Hi Siddarth,

You have a 4 cm cube, so the surface area is 4*4(area of one side)*6 sides..= 96, which you agree with.
Then figure out how many 1 cm cubes can fit into 4 cm cube. 4 cm cube's Volume is 4*4*4 = 64.
A 1 cm cube's Volume is 1*1*1 = 1 so 64/1 = 64 little cubes.

Now for the surface area of each little cube: 1*1(area of one side of one cube) * 6 sides= 6 surface area of one cube.
So, 64 cubes * 6 surface area/cube = 384 Total surface area.

So, 384 new/96 old is 4 times or 400% so 300% difference or 288 (difference in area)/96 (original) = 3 or 300% difference.
1 KUDOS received
Intern
Intern
avatar
Joined: 24 Sep 2008
Posts: 19
Followers: 0

Kudos [?]: 53 [1] , given: 0

Re: A 4 cm cube is cut into 1 cm cubes. [#permalink] New post 09 Oct 2008, 03:03
1
This post received
KUDOS
Original Surface Area= 6 x 4 x 4 = 96
new surface area per cube 6 x 1 x 1 = 6
Number of new cubes 4/1 = 4

so total new area = 6 * 4 = 24

96/24 = 4 so 400% (e) is the correct one :)

Is it ? It should be lol

Please update
Thanks
1 KUDOS received
CIO
CIO
avatar
Joined: 02 Oct 2007
Posts: 1218
Followers: 87

Kudos [?]: 656 [1] , given: 334

GMAT ToolKit User GMAT Tests User
Re: A 4 cm cube is cut into 1 cm cubes. [#permalink] New post 09 Oct 2008, 03:20
1
This post received
KUDOS
We have to find the percentage increase of the surface area and not just the ratio. It has to be 300% (D).

We had 1 cube with a side of 4 cm and after cutting we have 64 cubes with a side of 1 cm.

kam wrote:
Original Surface Area= 6 x 4 x 4 = 96
new surface area per cube 6 x 1 x 1 = 6
Number of new cubes 4/1 = 4

so total new area = 6 * 4 = 24

96/24 = 4 so 400% (e) is the correct one :)

Is it ? It should be lol

Please update
Thanks

_________________

Welcome to GMAT Club! :)
Facebook TwitterGoogle+LinkedIn
Want to solve GMAT questions on the go? GMAT Club iPhone app will help.
Please read this before posting in GMAT Club Tests forum
Result correlation between real GMAT and GMAT Club Tests
Are GMAT Club Test sets ordered in any way?

Take 15 free tests with questions from GMAT Club, Knewton, Manhattan GMAT, and Veritas.

Get the best GMAT Prep Resources with GMAT Club Premium Membership

1 KUDOS received
Intern
Intern
avatar
Joined: 24 Sep 2008
Posts: 19
Followers: 0

Kudos [?]: 53 [1] , given: 0

Re: A 4 cm cube is cut into 1 cm cubes. [#permalink] New post 09 Oct 2008, 03:50
1
This post received
KUDOS
O ya.. its % precent incrase problem :(

man these small stupid mistakes are bugging me :x
3 KUDOS received
Senior Manager
Senior Manager
User avatar
Joined: 29 Mar 2008
Posts: 350
Followers: 4

Kudos [?]: 48 [3] , given: 0

GMAT Tests User
Re: Cube's Surface Area [#permalink] New post 29 Oct 2008, 09:32
3
This post received
KUDOS
(d) 300%

Before cutting:Side:4cm
Surface Area= 6a^2. = 6*16=96 cm^2
Volume= a^3=64cm^3

After cutting:
side: 1cm
Volume= 1cm^3.

Since the total volume remains the same before and after.
# of 1cm cubes = 64/1 = 64

Therefore, SA of 1cm cubes after cutting = 64* (6 a^2) = 64*6=384

% increase= (before-after)/before
= (288/96)*100 = 300%.
_________________

To find what you seek in the road of life, the best proverb of all is that which says:
"Leave no stone unturned."
-Edward Bulwer Lytton

Current Student
avatar
Joined: 28 Dec 2004
Posts: 3405
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 13

Kudos [?]: 158 [0], given: 2

GMAT Tests User
Re: Cube's Surface Area [#permalink] New post 29 Oct 2008, 09:37
easiest way is to get the volume, of the big cube, which is 64 cm cube..

smalle cube each will 1 cube volume there fore there are 64 such small cubes

surface area =64 and big one has 16..difference is 48/16*100 or 300%
Director
Director
User avatar
Joined: 25 Oct 2006
Posts: 652
Followers: 7

Kudos [?]: 187 [0], given: 6

GMAT Tests User
Re: PS: Cubes GMAT Test m01 [#permalink] New post 30 Mar 2009, 22:23
IMO D - 300%

total 4*4*4 = 64 squares with side 1cm
total surface area = 64 * 6 cm square
surface area for 4cm cube is = 16 * 6 cm square

so surface area increase = (64-16)/16 * 100 = 300%
_________________

If You're Not Living On The Edge, You're Taking Up Too Much Space

1 KUDOS received
Director
Director
User avatar
Joined: 01 Apr 2008
Posts: 909
Schools: IIM Lucknow (IPMX) - Class of 2014
Followers: 15

Kudos [?]: 205 [1] , given: 18

GMAT Tests User
Re: PS: Cubes GMAT Test m01 [#permalink] New post 30 Mar 2009, 23:13
1
This post received
KUDOS
Agreed.
SA of bigger cube = 6l^2

SA of smaller cubes = 64*(6*(l/4)^2) = 24l^2

%increase = 24-6/6 *100 % = 300%
priyankur_saha@ml.com wrote:
IMO D - 300%

total 4*4*4 = 64 squares with side 1cm
total surface area = 64 * 6 cm square
surface area for 4cm cube is = 16 * 6 cm square

so surface area increase = (64-16)/16 * 100 = 300%
Manager
Manager
User avatar
Joined: 11 Apr 2009
Posts: 212
Followers: 3

Kudos [?]: 40 [0], given: 4

GMAT Tests User
Re: PS: Cubes GMAT Test m01 [#permalink] New post 17 Apr 2009, 03:35
gmat911 wrote:
priyankur_saha@ml.com wrote:
IMO D - 300%

total 4*4*4 = 64 squares with side 1cm
total surface area = 64 * 6 cm square
surface area for 4cm cube is = 16 * 6 cm square

so surface area increase = (64-16)/16 * 100 = 300%


how did you know that there were going to be 64 additional squares?



it is 300% - I like how one of the participants just used l and did not input a variable in.
one knows that there are 64 additional squares because discussed 3-dim shapes are cubes therefore all sides are equal.
Consequently one can fit (4)/(1) lengths into one dimension = 4. So 4 little cubes in on dimension and then cube it.

Hmmm that was a bit complicated - hope that made sense.

che
dg
_________________

-talent is the desire to practice-

Senior Manager
Senior Manager
User avatar
Joined: 13 Dec 2009
Posts: 264
Followers: 10

Kudos [?]: 104 [0], given: 13

GMAT Tests User Reviews Badge
Re: M01 #11 [#permalink] New post 19 Mar 2010, 06:41
elmagnifico wrote:
A 4 cm cube is cut into 1 cm cubes. What is the percentage increase in the surface area after such cutting?

(A) 4%
(B) 166%
(C) 266%
(D) 300%
(E) 400%

[Reveal] Spoiler: OA
D

Source: GMAT Club Tests - hardest GMAT questions

please provide detailed explanation.


surface area of 4 m cube = 6*4*4
surface area of 1 m cube = 6
no of cubes = 4*4*4
increase in surface area = (4*4*4*6 - 6*4*4)*100/6*4*4 = 300%
hence D
_________________

My debrief: done-and-dusted-730-q49-v40

SVP
SVP
avatar
Joined: 16 Nov 2010
Posts: 1691
Location: United States (IN)
Concentration: Strategy, Technology
Followers: 30

Kudos [?]: 288 [0], given: 36

GMAT Tests User Premium Member Reviews Badge
Re: M01 #11 [#permalink] New post 18 Mar 2011, 06:32
New surface area = 64 * 6 * (1)^2

Old Surface Area = 6 * (4)^2

So %age increase = {64 * 6 * (1)^2 - 6 * (4)^2}/6 * (4)^2 *100

= (64 - 16)/16 * 100 = 48/16 * 100 = 300 %

Answer : D
_________________

Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Intern
Intern
User avatar
Joined: 10 Jan 2011
Posts: 1
Followers: 0

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

Re: M01 #11 [#permalink] New post 18 Mar 2011, 11:59
I got E because I never read the instructions... I was just like "Oh, 16 is 400% of 4, E!", I better keep track of this mistake in the future...
Director
Director
avatar
Joined: 01 Feb 2011
Posts: 770
Followers: 14

Kudos [?]: 82 [0], given: 42

GMAT Tests User
Re: M01 #11 [#permalink] New post 18 Mar 2011, 15:51
Total surface area of initial cube = 6(4^2) = 96
Total surface area of final cube = 64 * 6 *(1^2)

% change = ((final cube area-initial cube area) / initial cube area)*100 = 300%
Manager
Manager
avatar
Joined: 02 Feb 2012
Posts: 195
Location: United States
GPA: 3.08
Followers: 1

Kudos [?]: 2 [0], given: 104

Re: M01 #11 [#permalink] New post 22 Mar 2012, 12:22
I got answer D 300%

Surface area of 4 cm cube = (surface area of one side)*(number of sides) = (4*4) * (6)
Surface area of all cubes: = (number of cubes)*(surface area of cube) = (4*4*4) * (6)

By simply looking at these two equations we see that there is 4 times more surface area with the little cubes, thus 300% increase.
Manager
Manager
avatar
Joined: 28 Apr 2011
Posts: 195
Followers: 0

Kudos [?]: 6 [0], given: 6

Re: M01 #11 [#permalink] New post 26 Mar 2012, 00:28
300%

Key to solve problem is to determine how many new cubes will be there......

Best approch= Original cube volume/ New cube volume
Manager
Manager
avatar
Status: I will not stop until i realise my goal which is my dream too
Joined: 25 Feb 2010
Posts: 235
Schools: Johnson '15
Followers: 2

Kudos [?]: 22 [0], given: 16

GMAT Tests User
Re: M01 #11 [#permalink] New post 26 Mar 2012, 06:07
a tricky one...i had failed....i will go with D(300%) after the explanations
_________________

Regards,
Harsha

Note: Give me kudos if my approach is right , else help me understand where i am missing.. I want to bell the GMAT Cat ;)

Satyameva Jayate - Truth alone triumphs

Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 22146
Followers: 3412

Kudos [?]: 24961 [0], given: 2698

Re: M01 #11 [#permalink] New post 26 Mar 2012, 06:41
Expert's post
elmagnifico wrote:
A 4 cm cube is cut into 1 cm cubes. What is the percentage increase in the surface area after such cutting?

(A) 4%
(B) 166%
(C) 266%
(D) 300%
(E) 400%

[Reveal] Spoiler: OA
D

Source: GMAT Club Tests - hardest GMAT questions

please provide detailed explanation.


A cube has 6 faces.

The surface area of a cube with the length of the side of 4 cm is 6*4^2=6*16 cm^2.

Now, since the volume of the big cube is 4^3=64 cm^3 and the volume of the smaller cubes is 1^3=1 cm^3, then when the big cube is cut into the smaller cubes we'll get 64/1=64 little cubes. Each of those little cubes will have the surface area equal to 6*1^2=6 cm^2, so total surface are of those 64 little cubes will be 6*64 cm^2.

6*64 is 4 times more than 6*16 which corresponds to 300% increase.

Answer: D.

Or: general formula for percent increase or decrease, (percent change): Percent=\frac{Change}{Original}*100

So the percent increase will be: Percent=\frac{Change}{Original}*100=\frac{6*64-6*16}{6*16}*100=300%.

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

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Re: M01 #11   [#permalink] 26 Mar 2012, 06:41
    Similar topics Author Replies Last post
Similar
Topics:
Experts publish their posts in the topic M01-11 Bunuel 1 27 Aug 2014, 13:14
Experts publish their posts in the topic m01 cgyuyo 1 27 May 2009, 10:20
4 M01 27 IanStewart 11 21 Aug 2008, 09:29
18 Experts publish their posts in the topic M01-Q15 goalsnr 20 16 Jul 2008, 20:25
Access to M01 Test Guest 1 27 Nov 2007, 12:31
Display posts from previous: Sort by

M01 #11

  Question banks Downloads My Bookmarks Reviews Important topics  

Go to page    1   2    Next  [ 27 posts ] 

Moderators: Bunuel, WoundedTiger



cron

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®.