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

 It is currently 17 Dec 2018, 04:24

# R1 Decisions:

Michigan Ross Chat (US calls are expected today)  |  UCLA Anderson Chat  (Calls expected to start at 7am PST; Applicants from Asia will hear first)

### 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

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

## Events & Promotions

###### Events & Promotions in December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
• ### 10 Keys to nail DS and CR questions

December 17, 2018

December 17, 2018

06:00 PM PST

07:00 PM PST

Join our live webinar and learn how to approach Data Sufficiency and Critical Reasoning problems, how to identify the best way to solve each question and what most people do wrong.
• ### R1 Admission Decisions: Estimated Decision Timelines and Chat Links for Major BSchools

December 17, 2018

December 17, 2018

10:00 PM PST

11:00 PM PST

From Dec 5th onward, American programs will start releasing R1 decisions. Chat Rooms: We have also assigned chat rooms for every school so that applicants can stay in touch and exchange information/update during decision period.

# 64 small identical cubes are used to form a large cube

Author Message
TAGS:

### Hide Tags

Senior Manager
Joined: 10 Apr 2012
Posts: 269
Location: United States
Concentration: Technology, Other
GPA: 2.44
WE: Project Management (Telecommunications)
64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

Updated on: 16 Apr 2013, 23:28
7
17
00:00

Difficulty:

75% (hard)

Question Stats:

58% (01:14) correct 42% (01:42) wrong based on 546 sessions

### HideShow timer Statistics

64 small identical cubes are used to form a large cube. How many more cubes are needed to add one top layer of small cube all over the surface of the large cube ?

A. 64
B. 128
C. 152
D. 216
E. 256

Originally posted by guerrero25 on 16 Apr 2013, 13:51.
Last edited by Bunuel on 16 Apr 2013, 23:28, edited 1 time in total.
Edited the question.
VP
Status: Far, far away!
Joined: 02 Sep 2012
Posts: 1063
Location: Italy
Concentration: Finance, Entrepreneurship
GPA: 3.8
Re: 64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

16 Apr 2013, 13:58
10
7
The side of the cube is N. The area is $$N^3=64$$ so $$N=4$$, there are 4 cubes on each side
To make this cube "one cube longer" we have to add one cube at both ends of a side $$1+4+1=6$$, the new cube will have an area of $$6^3=216$$ cubes.

The difference in the areas will be the number of cubes we've added: $$216-64=152$$

C
_________________

It is beyond a doubt that all our knowledge that begins with experience.

Kant , Critique of Pure Reason

Tips and tricks: Inequalities , Mixture | Review: MGMAT workshop
Strategy: SmartGMAT v1.0 | Questions: Verbal challenge SC I-II- CR New SC set out !! , My Quant

Rules for Posting in the Verbal Forum - Rules for Posting in the Quant Forum[/size][/color][/b]

##### General Discussion
Math Expert
Joined: 02 Sep 2009
Posts: 51259
Re: 64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

16 Apr 2013, 23:32
1
3
guerrero25 wrote:
64 small identical cubes are used to form a large cube. How many more cubes are needed to add one top layer of small cube all over the surface of the large cube ?

A. 64
B. 128
C. 152
D. 216
E. 256

Similar questions to practice:
a-big-cube-is-formed-by-rearranging-the-160-coloured-and-99424.html
a-large-cube-consists-of-125-identical-small-cubes-how-110256.html

Hope it helps.
_________________
Manager
Joined: 04 Mar 2013
Posts: 60
Location: India
Concentration: Strategy, Operations
Schools: Booth '17 (M)
GMAT 1: 770 Q50 V44
GPA: 3.66
WE: Operations (Manufacturing)
Re: 64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

17 Apr 2013, 04:43
2
2
Another way of solving this

Since the volume is 64 so the side must be 4 units each

The total no. of unit cubes to "coat" the bigger cube would be as

4^2=16 cubes to cover each face so 16*6=96
4 cubes on each edge so 4*12 = 48
one at each corner so 8

_________________

When you feel like giving up, remember why you held on for so long in the first place.

Intern
Joined: 21 Jun 2013
Posts: 31
Re: 64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

21 Sep 2013, 04:08
aceacharya wrote:
Another way of solving this

Since the volume is 64 so the side must be 4 units each

The total no. of unit cubes to "coat" the bigger cube would be as

4^2=16 cubes to cover each face so 16*6=96
4 cubes on each edge so 4*12 = 48
one at each corner so 8

Hi! I did not understand why you did 4^2, and why 8 more cubes are required at the corners.
Manager
Joined: 10 Sep 2013
Posts: 76
Re: 64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

21 Sep 2013, 05:20
1
vjns wrote:
aceacharya wrote:
Another way of solving this

Since the volume is 64 so the side must be 4 units each

The total no. of unit cubes to "coat" the bigger cube would be as

4^2=16 cubes to cover each face so 16*6=96
4 cubes on each edge so 4*12 = 48
one at each corner so 8

Hi! I did not understand why you did 4^2, and why 8 more cubes are required at the corners.

The 4^ 2 is because there are 4 cubes on one side of the face. A face has 4 sides ( which makes it a square), so one face has 4+4+4+4 = 16 cubes.
Then, there are 6 faces, so 16*6 = 96 cubes
There are also 4 cubes on each edge = 4*12= 48
and since there are 8 corners in a big cube ( 4 that you can see, 4 at the back, and one at the bottom that you cant see). If you draw a cube and try counting the edges you'll find 8 edges
_________________

Kudos if I helped

Intern
Joined: 14 May 2014
Posts: 41
Re: 64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

20 May 2014, 08:51
1
1
64 small cube will make a large cube with 4 cubes in each line i.e.
Adding one layer will require one cube at each end and hence new cube will have 6 cubes in each line.

Total number of small cubes in new cube = 6^3 = 216

Extra cube required = 216 - 64 = 152

_________________

Help me with Kudos if it helped you "

Mathematics is a thought process.

SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1825
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Re: 64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

23 May 2014, 02:07
Smaller cube = 4 x 4 x 4

Larger cube possible = 6 x 6 x 6

Two sides = 6 * 6 * 2 = 72

Remaining 4 sides = 16 * 4 = 64

4 corners = 4 * 4 = 16

Total = 72 + 64 + 16 = 152
_________________

Kindly press "+1 Kudos" to appreciate

Manager
Joined: 17 Nov 2014
Posts: 51
Location: India
Re: 64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

15 May 2016, 00:35
1
Let the side of the cube is x. The area is X^3=64 X=4 , there are 4 cubes on each side
To add one top layer of small cube all over the surface of the large cube.
we have to add one cube at both ends of a side 1+4+1=6, the new cube will have =216 cubes.

The difference in the number of cubes we've added: 216−64=152

C
Manager
Joined: 20 Feb 2017
Posts: 73
Re: 64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

28 Jun 2017, 10:13
Zarrolou wrote:
The side of the cube is N. The area is $$N^3=64$$ so $$N=4$$, there are 4 cubes on each side
To make this cube "one cube longer" we have to add one cube at both ends of a side $$1+4+1=6$$, the new cube will have an area of $$6^3=216$$ cubes.

The difference in the areas will be the number of cubes we've added: $$216-64=152$$

C

Why you have mentioned 'area' where as you have calculated 'volume'?
Director
Joined: 14 Dec 2017
Posts: 518
Location: India
Re: 64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

06 Jul 2018, 00:19
guerrero25 wrote:
64 small identical cubes are used to form a large cube. How many more cubes are needed to add one top layer of small cube all over the surface of the large cube ?

A. 64
B. 128
C. 152
D. 216
E. 256

Given 64 small cubes are used to form a large cube.

Consider the smaller cube with dimensions of 1 unit each. We get volume of each smaller cube = 1 cubic unit

The larger cube will have a volume = 64 cubic units = 4^3 cubic units.

Hence the larger cube has dimensions as 4 units & is made of 64 cubes.

Now if we want to add a top layer of cubes on each surface, hence we are increasing the dimensions of the larger cube by 1 unit in all directions.

Hence the height of the cube will be increased by 1 unit on the top & by 1 unit on the bottom. Similarly for length & width.

We get a new larger cube of dimensions 6 units. Its volume = 6^3 = 216 cubic units & is made of 216 cubes.

Therefore the no. of additional cubes required = 216 - 64 = 152 cubes

Thanks,
GyM
_________________
RC Moderator
Joined: 24 Aug 2016
Posts: 576
Concentration: Entrepreneurship, Operations
GMAT 1: 630 Q48 V28
GMAT 2: 540 Q49 V16
Re: 64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

10 Nov 2018, 16:59
According to the Q, we have a cube stack of 4 at every axis of a 3d plane : 4^3=64
As we need to add 1 layer at each side we need a total stack of (1+4+1)^3 = 216 cubes
Thus , small cubes required to meet the cond : 216-64 =152.... Ans C
_________________

Please let me know if I am going in wrong direction.
Thanks in appreciation.

Intern
Joined: 10 May 2018
Posts: 34
Re: 64 small identical cubes are used to form a large cube  [#permalink]

### Show Tags

22 Nov 2018, 14:13
guerrero25 wrote:
64 small identical cubes are used to form a large cube. How many more cubes are needed to add one top layer of small cube all over the surface of the large cube ?

A. 64
B. 128
C. 152
D. 216
E. 256

It's a 4 x 4 x 4 cube.

An extra layer will make it 6 x 6 x 6 cube (a cube on each side will increase each edge by 2 cubes)

Difference = 6^3 - 4^3 = 216 - 64 = 152

Re: 64 small identical cubes are used to form a large cube &nbs [#permalink] 22 Nov 2018, 14:13
Display posts from previous: Sort by