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.
It appears that you are browsing the GMAT Club forum unregistered!
Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club
Registration gives you:
Tests
Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.
Applicant Stats
View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more
Books/Downloads
Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!
Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
A big cube is formed by rearranging the 160 coloured and 56 [#permalink]
19 Aug 2010, 03:41
15
This post received KUDOS
36
This post was BOOKMARKED
00:00
A
B
C
D
E
Difficulty:
95% (hard)
Question Stats:
34% (03:37) correct
66% (02:39) wrong based on 1137 sessions
A big cube is formed by rearranging the 160 coloured and 56 non-coloured similar cubes in such a way that the exposure of the coloured cubes to the outside is minimum. The percentage of exposed area to the coloured is :
A big cube is formed by rearranging the 160 coloured and 56 non-coloured similar cubes in such a way that the exposure of the coloured cubes to the outside is minimum. The percentage of exposed area to the coloured is :
1) 25.9% 2) 44.44% 3) 35% 4) 61% 5) None of these
200 cubes will be exposed outside and 16 cubes will be inside which will not be exposed at all.
To minimise the coloured area 16 coloured cubes will be used inside and rest outside.
So total 144 coloured cubes + 56 non-coloured cubes will be used outside.
The percentage of exposed area to the coloured\(= \frac{200}{144} *100=139 % ( approx)\)
A big cube is formed by rearranging the 160 coloured and 56 non-coloured similar cubes in such a way that the exposure of the coloured cubes to the outside is minimum. The percentage of exposed area THAT is coloured is:
1) 25.9% 2) 44.44% 3) 35% 4) 61% 5) None of these
Good question, +1. Though I think there is a little typo, the question should be: "The percentage of exposed area THAT is coloured is:"
We have 160+56=216=6^3 big cube.
Non exposed will be 4^3 little cubes, which will be "inside" the big cube, so exposed will be 216-4^3=152 little cubes out of which there will be 152-56=96 colored cube (as colored cubes are minimized on the surface).
Now surface area of big cube is 6*36=216 (exposed area) out of which the area of 96 is colored, so the percentage of exposed area THAT is coloured is --> \(\frac{96}{216}\approx(0.4444)=44.44%\).
A big cube is formed by rearranging the 160 coloured and 56 non-coloured similar cubes in such a way that the exposure of the coloured cubes to the outside is minimum. The percentage of exposed area THAT is coloured is:
1) 25.9% 2) 44.44% 3) 35% 4) 61% 5) None of these
Good question, +1. Though I think there is a little typo, the question should be: "The percentage of exposed area THAT is coloured is:"
We have 160+56=216=6^6 big cube.
Non exposed will be 4^3 little cubes, which will be "inside" the big cube, so exposed will be 216-4^3=152 little cubes out of which there will be 152-56=96 colored cube (as colored cubes are minimized on the surface).
Now surface area of big cube is 6*36=216 (exposed area) out of which the area of 96 is colored, so the percentage of exposed area THAT is coloured is --> \(\frac{96}{216}\approx(0.4444)=44.44%\).
Answer: B.
Bunuel,
Can you please explain how did you get that non exposed cubes will be 4 ^3 cubes? I always tend to get confused with questions like these and try to use the brute force to calculate the number of exposed or non exposed cubes.
A big cube is formed by rearranging the 160 coloured and 56 non-coloured similar cubes in such a way that the exposure of the coloured cubes to the outside is minimum. The percentage of exposed area THAT is coloured is:
1) 25.9% 2) 44.44% 3) 35% 4) 61% 5) None of these
Good question, +1. Though I think there is a little typo, the question should be: "The percentage of exposed area THAT is coloured is:"
We have 160+56=216=6^6 big cube.
Non exposed will be 4^3 little cubes, which will be "inside" the big cube, so exposed will be 216-4^3=152 little cubes out of which there will be 152-56=96 colored cube (as colored cubes are minimized on the surface).
Now surface area of big cube is 6*36=216 (exposed area) out of which the area of 96 is colored, so the percentage of exposed area THAT is coloured is --> \(\frac{96}{216}\approx(0.4444)=44.44%\).
Answer: B.
Bunuel,
Can you please explain how did you get that non exposed cubes will be 4 ^3 cubes? I always tend to get confused with questions like these and try to use the brute force to calculate the number of exposed or non exposed cubes.
Cheers,
Well the big cube which has the side built with 6 little cubes (6^3) will have "inside" the cube which has the side built with 4 little cubes (6-2 edges), so 4^3... Similarly, the cube which has the side built with 4 little cubes (4^3) will have "inside" the cube which has the side built with 2 little cubes, (4-2 edges), so 2^3... _________________
Well the big cube which has the side built with 6 little cubes (6^3) will have "inside" the cube which has the side built with 4 little cubes (6-2 edges), so 4^3... Similarly, the cube which has the side built with 4 little cubes (4^3) will have "inside" the cube which has the side built with 2 little cubes, (4-2 edges), so 2^3...
Well the big cube which has the side built with 6 little cubes (6^3) will have "inside" the cube which has the side built with 4 little cubes (6-2 edges), so 4^3... Similarly, the cube which has the side built with 4 little cubes (4^3) will have "inside" the cube which has the side built with 2 little cubes, (4-2 edges), so 2^3...
Nice explanation "Bunuel", you got it absolutely correct. It took me lot of time to get the concept and the answer.
A big cube is formed by rearranging the 160 coloured and 56 non-coloured similar cubes in such a way that the exposure of the coloured cubes to the outside is minimum. The percentage of exposed area THAT is coloured is:
1) 25.9% 2) 44.44% 3) 35% 4) 61% 5) None of these
Good question, +1. Though I think there is a little typo, the question should be: "The percentage of exposed area THAT is coloured is:"
We have 160+56=216=6^6 big cube.
Non exposed will be 4^3 little cubes, which will be "inside" the big cube, so exposed will be 216-4^3=152 little cubes out of which there will be 152-56=96 colored cube (as colored cubes are minimized on the surface).
Now surface area of big cube is 6*36=216 (exposed area) out of which the area of 96 is colored, so the percentage of exposed area THAT is coloured is --> \(\frac{96}{216}\approx(0.4444)=44.44%\).
Answer: B.
Thanks for an explanation of the "cube" concept but here is a question. Why did you divide the number of outside colored cubes by the number of all small cubes? The questions asks about relationship of exposed area and the coloured cubes.
A big cube is formed by rearranging the 160 coloured and 56 non-coloured similar cubes in such a way that the exposure of the coloured cubes to the outside is minimum. The percentage of exposed area THAT is coloured is:
1) 25.9% 2) 44.44% 3) 35% 4) 61% 5) None of these
Good question, +1. Though I think there is a little typo, the question should be: "The percentage of exposed area THAT is coloured is:"
We have 160+56=216=6^6 big cube.
Non exposed will be 4^3 little cubes, which will be "inside" the big cube, so exposed will be 216-4^3=152 little cubes out of which there will be 152-56=96 colored cube (as colored cubes are minimized on the surface).
Now surface area of big cube is 6*36=216 (exposed area) out of which the area of 96 is colored, so the percentage of exposed area THAT is coloured is --> \(\frac{96}{216}\approx(0.4444)=44.44%\).
Answer: B.
Thanks for an explanation of the "cube" concept but here is a question. Why did you divide the number of outside colored cubes by the number of all small cubes? The questions asks about relationship of exposed area and the coloured cubes.
We are asked to find the ratio of colored area to whole surface area. Colored area is 96, as 96 cubes are exposed.Total surface area is: 6 faces * area of one face =6*(6*6)=216.
Thanks for answer but it seems I haven't got something. I thought we have 64 cubes inside ( the smaller inside cube, 4x4x4). As I understood they aren't exposed and we have to exlude them from 216.
Just a thought... But if the number of non colored cubes was to be 30 and the number of colored cubes 186, then it would have made the problem a whole lot tougher. Assuming that all the sides of the colored cubes are indeed colored, they would need to be placed at the edges and corners first to increase the surface are that is colored.
Re: A big cube is formed by rearranging the 160 coloured and 56 [#permalink]
14 Aug 2013, 10:56
15
This post received KUDOS
1
This post was BOOKMARKED
A big cube is formed by rearranging the 160 colored and 56 non-colored similar cubes in such a way that the exposure of the colored cubes to the outside is minimum. The percentage of exposed area that is colored:
A. 25.9% B. 44.44% C. 35% D. 61% E. None of these ...... My explanation and diagram:
Re: A big cube is formed by rearranging the 160 coloured and 56 [#permalink]
21 Aug 2013, 10:28
1
This post received KUDOS
Asifpirlo wrote:
A big cube is formed by rearranging the 160 colored and 56 non-colored similar cubes in such a way that the exposure of the colored cubes to the outside is minimum. The percentage of exposed area that is colored:
A. 25.9% B. 44.44% C. 35% D. 61% E. None of these ...... My explanation and diagram:
Mind blowing excellent Figure... _________________
Re: A big cube is formed by rearranging the 160 coloured and 56 [#permalink]
21 Aug 2013, 10:32
3
This post received KUDOS
Expert's post
1
This post was BOOKMARKED
mission2009 wrote:
A big cube is formed by rearranging the 160 coloured and 56 non-coloured similar cubes in such a way that the exposure of the coloured cubes to the outside is minimum. The percentage of exposed area to the coloured is :
Re: A big cube is formed by rearranging the 160 coloured and 56 [#permalink]
23 Aug 2013, 10:31
Bunuel,
The percentage of exposed area that is colored will be: Number of colored cubes exposed (96)/Total number of cubes which are exposed(152=216-64)
Please clarify this. I think the question needs to be worded more specifically such as, The %tage of colored cubes which are exposed or something on similar lines. _________________
Re: A big cube is formed by rearranging the 160 coloured and 56 [#permalink]
20 Sep 2013, 20:48
vabhs192003 wrote:
Bunuel,
The percentage of exposed area that is colored will be: Number of colored cubes exposed (96)/Total number of cubes which are exposed(152=216-64)
Please clarify this. I think the question needs to be worded more specifically such as, The %tage of colored cubes which are exposed or something on similar lines.
I think this question arose because one small thing in Bunuel's answer is missing. 96 is not only a number of colored сubes exposed, but also the exposed surface area of these сubes. only 1 side of each of 96 colored сubes will be exposed. 216 is the total exposed surface area of all 216 cubes (hope no questions with that). We are asked for "The percentage of exposed area that is coloured", thus, 96/216 = 0.4444.
And I totally agree with earlier note of ashivapu, in case the number of colored cubes were more than 160, the questions would be even tougher!
Re: A big cube is formed by rearranging the 160 coloured and 56 [#permalink]
29 Oct 2013, 10:16
1
This post was BOOKMARKED
Good question
Out of the 216 cubes:
64 (4^3) can be used to create the middle 4by4 cube - use all color cubes for this
152 (216 - 96) will have at least one face showing on the outside. out of these
96 will have one side showing - use all color cubes (6 sides * 4^2 on each side) 48 will have two sides showing - use all non-color cubes (12 edges with 4 cubes each) 8 will have three sides showing at the corners - use all non-color cubes
so the percentage is 96 / (6^3). you could also count the faces for the area 96*1 / (96*1 + 48*2 + 8*3).
Great solution Bunuel
gmatclubot
Re: A big cube is formed by rearranging the 160 coloured and 56
[#permalink]
29 Oct 2013, 10:16
The “3 golden nuggets” of MBA admission process With ten years of experience helping prospective students with MBA admissions and career progression, I will be writing this blog through...
You know what’s worse than getting a ding at one of your dreams schools . Yes its getting that horrid wait-listed email . This limbo is frustrating as hell . Somewhere...