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 large solid cube is assembled by gluing together identical [#permalink]

Show Tags

18 Apr 2013, 00:01

4

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

45% (medium)

Question Stats:

74% (02:27) correct
26% (02:02) wrong based on 121 sessions

HideShow timer Statistics

A large solid cube is assembled by gluing together identical unpainted small cubic blocks. All six faces of the large cube are then painted red. If exactly 27 of the small cubic blocks that make up the large cube have no red paint on them, how many small cubic blocks make up the larger cube?

Re: A large solid cube is assembled by gluing together identical [#permalink]

Show Tags

18 Apr 2013, 01:49

2

This post received KUDOS

usre123 wrote:

Thankyou for taking the time to answer, but I dont understand. Why is the side 3? And why have you added 1+1+3? Also, as I explained in the pm, we got a handout of these in our gmat class, and the questions just had one single answer. So I dont have the five answer choices.

The inner cube has an area of 27, we know that the area of a coube is \(side^3\) so in this case \(s^3=27\) so \(s=3\) The inner cube has a side of 3. Good!

Moving on... This is an inner cube, so is contained in a larger cube. The larger cube must contain the inner cube, and this is possible only if the larger cube has at the end of each side one more cube (look at the image: it's in 2D but the concept is the same) So we add 1 cube to each side 1+3+1=5, the larger cube has a side of 5 => \(area=5^3=125\)

Hope it's clear now, let me know

Attachments

cube.jpg [ 9.94 KiB | Viewed 4602 times ]

_________________

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

Re: A large solid cube is assembled by gluing together identical [#permalink]

Show Tags

18 Apr 2013, 05:05

1

This post received KUDOS

usre123 wrote:

A large solid cube is assembled by gluing together identical unpainted small cubic blocks. All six faces of the large cube are then painted red. If exactly 27 of the small cubic blocks that make up the large cube have no red paint on them, how many small cubic blocks make up the larger cube?

Re: A large solid cube is assembled by gluing together identical [#permalink]

Show Tags

19 Apr 2013, 21:35

Area of a cube is side squared into 6, for six faces. Here your calculationg the volume by saying side cubed. Just that part i dont get. Why are we calculating volume? Thanks. Also, youve added one to each side. But we could add any number, such as two etc. And it would change the total blocks...

Re: A large solid cube is assembled by gluing together identical [#permalink]

Show Tags

19 Apr 2013, 23:07

usre123 wrote:

Area of a cube is side squared into 6, for six faces. Here your calculationg the volume by saying side cubed. Just that part i dont get. Why are we calculating volume? Thanks. Also, youve added one to each side. But we could add any number, such as two etc. And it would change the total blocks...

Hi usre123,

We know that the inner cube has an area of 27, to find the side of a cube (with the area) we have to use \(side^3=Area\) and that exactly what we do here. The formula for the area of the cube is not much helpful here...

The second question is a good one, and the answer is in the main question itself. We cannot add more than one cube because EXACTLY 27 cubes are not painted, if we add more than 1 cube, than the number of not painted cubes will be more than 27.

Hope this helps, let me know
_________________

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

Re: A large solid cube is assembled by gluing together identical [#permalink]

Show Tags

20 Sep 2013, 08:41

This is a gr8 example of a situation when you are running short of time during the exam. To make up a cubic block using smaller cubic blocks we would always need \(a^3\) no of blocks.

And 125 is the only option which is a perfect cube of an integer i.e. 125 = \((5)^3\)
_________________

Do not forget to hit the Kudos button on your left if you find my post helpful

A large solid cube is assembled by gluing together identical unpainted small cubic blocks. All six faces of the large cube are then painted red. If exactly 27 of the small cubic blocks that make up the large cube have no red paint on them, how many small cubic blocks make up the larger cube?

Re: A large solid cube is assembled by gluing together identical [#permalink]

Show Tags

20 Apr 2016, 03:43

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Best Schools for Young MBA Applicants Deciding when to start applying to business school can be a challenge. Salary increases dramatically after an MBA, but schools tend to prefer...

Marty Cagan is founding partner of the Silicon Valley Product Group, a consulting firm that helps companies with their product strategy. Prior to that he held product roles at...