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
OA C
64 small identical cubes are used to form a large cube
This topic has expert replies
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
64 cubes will create a 4x4x4 large cube.guerrero 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
OA C
If we add at top layer to all of the sides, we get a larger 6x6x6 cube
A 6x6x6 cube requires 216 cubes.
216 - 64 = 152, so the answer is C
Cheers,
Brent
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
I guess it comes down to whether the smaller cube's surface is covered if the edges are exposed. Given the potential for ambiguity, this question might not be GMAT-worthy.J N wrote:Poorly worded question.
If you only need to cover the existing surface area of 4x4x4 cube then need 96 more cubes.
Cheers
Brent
-
- Master | Next Rank: 500 Posts
- Posts: 468
- Joined: Mon Jul 25, 2011 10:20 pm
- Thanked: 29 times
- Followed by:4 members