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

 It is currently 21 Aug 2018, 23:01

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

A cube with volume 27 is cut into 8 smaller cubes having equal volumes

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

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 48117
A cube with volume 27 is cut into 8 smaller cubes having equal volumes  [#permalink]

Show Tags

06 Dec 2017, 05:33
00:00

Difficulty:

(N/A)

Question Stats:

72% (01:43) correct 28% (01:37) wrong based on 36 sessions

HideShow timer Statistics

A cube with volume 27 is cut into 8 smaller cubes having equal volumes. What is the difference between the surface area of the original cube and the surface area of one of the smaller cubes?

(A) 45.25
(B) 40.5
(C) 27
(D) 24.38
(E) 19

_________________
Intern
Joined: 16 Oct 2017
Posts: 30
Location: Ireland
Concentration: Healthcare, Finance
Re: A cube with volume 27 is cut into 8 smaller cubes having equal volumes  [#permalink]

Show Tags

06 Dec 2017, 05:56
[quote="Bunuel"]A cube with volume 27 is cut into 8 smaller cubes having equal volumes. What is the difference between the surface area of the original cube and the surface area of one of the smaller cubes?

(A) 45.25
(B) 40.5
(C) 27
(D) 24.38
(E) 19

Original:
$$a^3 = 27$$
$$a = 3$$
$$6a^2 = 54$$

Cut one:
$$a^3 = \frac{27}{8}$$
$$a = \frac{3}{2}$$
$$6a^2 = 13.5$$

$$54 - 13.5 = 40.5$$ (B is the answer)
Intern
Joined: 26 Oct 2017
Posts: 28
Re: A cube with volume 27 is cut into 8 smaller cubes having equal volumes  [#permalink]

Show Tags

06 Dec 2017, 05:56
Bunuel wrote:
A cube with volume 27 is cut into 8 smaller cubes having equal volumes. What is the difference between the surface area of the original cube and the surface area of one of the smaller cubes?

(A) 45.25
(B) 40.5
(C) 27
(D) 24.38
(E) 19

Answer is B IMO

Sent from my ONEPLUS A3003 using GMAT Club Forum mobile app
Intern
Joined: 22 Mar 2017
Posts: 4
Location: India
Re: A cube with volume 27 is cut into 8 smaller cubes having equal volumes  [#permalink]

Show Tags

06 Dec 2017, 11:16
Bigger cube has each side measuring 3, SA is 54. Smaller will have each side measuring half of the bigger cube, 1.5. SA of smaller cube is 13.5. So the answer is B, 40.5

Sent from my Redmi Note 3 using GMAT Club Forum mobile app
Intern
Joined: 22 Mar 2017
Posts: 4
Location: India
Re: A cube with volume 27 is cut into 8 smaller cubes having equal volumes  [#permalink]

Show Tags

06 Dec 2017, 11:18
lesner19 wrote:
Bunuel wrote:
A cube with volume 27 is cut into 8 smaller cubes having equal volumes. What is the difference between the surface area of the original cube and the surface area of one of the smaller cubes?

(A) 45.25
(B) 40.5
(C) 27
(D) 24.38
(E) 19

Answer is B IMO

Sent from my ONEPLUS A3003 using GMAT Club Forum mobile app

Interesting approach [THUMBS UP SIGN]
Manager
Joined: 01 Feb 2017
Posts: 155
A cube with volume 27 is cut into 8 smaller cubes having equal volumes  [#permalink]

Show Tags

08 Dec 2017, 13:57
Whenever a cube is divided into 8 parts, the ratio of side original: small is 2:1.

Now, as side of original cube is 3, side of small cube must be 1.5.

Difference in SA= (6*3^2)-(6*1.5^2)= 6(9-2.25)= 6*6.75= 6*(6+0.75)= 36+(6*3/4)= 36+4.5= 40.5

Ans B

Posted from my mobile device
A cube with volume 27 is cut into 8 smaller cubes having equal volumes &nbs [#permalink] 08 Dec 2017, 13:57
Display posts from previous: Sort by

A cube with volume 27 is cut into 8 smaller cubes having equal volumes

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

Events & Promotions

 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®.