Author 
Message 
TAGS:

Hide Tags

Director
Joined: 29 Nov 2012
Posts: 878

If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
09 Jan 2013, 21:07
2
This post received KUDOS
11
This post was BOOKMARKED
Question Stats:
65% (02:06) correct
35% (01:11) wrong based on 303 sessions
HideShow timer Statistics
If a certain cube has Volume V and a second cube has twice the surface area of the first cube, what is the volume of the second cube in terms of V? A. \(\sqrt{2}V\) B. \(2\sqrt{2}V\) C. 2V D. 4V E. 8V
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
Click +1 Kudos if my post helped...
Amazing Free video explanation for all Quant questions from OG 13 and much more http://www.gmatquantum.com/og13th/
GMAT Prep software What if scenarios http://gmatclub.com/forum/gmatprepsoftwareanalysisandwhatifscenarios146146.html



Moderator
Joined: 02 Jul 2012
Posts: 1223
Location: India
Concentration: Strategy
GPA: 3.8
WE: Engineering (Energy and Utilities)

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
09 Jan 2013, 22:16
6
This post received KUDOS
1
This post was BOOKMARKED
Let volume of cube be = 1 Surface area = 6 Surface area of 2nd cube = 12 Side of second cube = \(\sqrt{2}\) Volume of second cube = \(2*\sqrt{2}\) Answer is B.
_________________
Did you find this post helpful?... Please let me know through the Kudos button.
Thanks To The Almighty  My GMAT Debrief
GMAT Reading Comprehension: 7 Most Common Passage Types



Director
Joined: 29 Nov 2012
Posts: 878

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
09 Jan 2013, 23:01
MacFauz wrote: Let volume of cube be = 1 Surface area = 6 Surface area of 2nd cube = 12 Side of second cube = \(\sqrt{2}\) Volume of second cube = \(2*\sqrt{2}\)
Answer is A. Everything is right I'm not sure how to write math functions here so A and B look similar, answer is B.
_________________
Click +1 Kudos if my post helped...
Amazing Free video explanation for all Quant questions from OG 13 and much more http://www.gmatquantum.com/og13th/
GMAT Prep software What if scenarios http://gmatclub.com/forum/gmatprepsoftwareanalysisandwhatifscenarios146146.html



Moderator
Joined: 02 Jul 2012
Posts: 1223
Location: India
Concentration: Strategy
GPA: 3.8
WE: Engineering (Energy and Utilities)

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
09 Jan 2013, 23:12
fozzzy wrote: MacFauz wrote: Let volume of cube be = 1 Surface area = 6 Surface area of 2nd cube = 12 Side of second cube = \(\sqrt{2}\) Volume of second cube = \(2*\sqrt{2}\)
Answer is A. Everything is right I'm not sure how to write math functions here so A and B look similar, answer is B. Oops.. Thanks for pointing that out.. Question formatted and answer changed..
_________________
Did you find this post helpful?... Please let me know through the Kudos button.
Thanks To The Almighty  My GMAT Debrief
GMAT Reading Comprehension: 7 Most Common Passage Types



Manager
Joined: 18 Oct 2011
Posts: 90
Location: United States
Concentration: Entrepreneurship, Marketing
GMAT Date: 01302013
GPA: 3.3

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
10 Jan 2013, 08:14
Plug in actual numbers. Use 2 as the side of the first cube. Surface area would equal 24 and volume would equal 8. For the surface area for the 2nd cube to be double (48) the 1st cube we would have sides of 2root2 and a volume of 16root2.
Therefore 8 x ? = 16root2....this only leaves 2root2



Intern
Joined: 10 Jan 2013
Posts: 9

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
10 Jan 2013, 19:31
MacFauz wrote: Let volume of cube be = 1 Surface area = 6 Surface area of 2nd cube = 12 Side of second cube = \(\sqrt{2}\) Volume of second cube = \(2*\sqrt{2}\)
Answer is B. I din't understand the side of the second cube...how do you derive a side from the Total Surface Area????



Director
Joined: 29 Nov 2012
Posts: 878

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
10 Jan 2013, 19:53
4112019 wrote: MacFauz wrote: Let volume of cube be = 1 Surface area = 6 Surface area of 2nd cube = 12 Side of second cube = \(\sqrt{2}\) Volume of second cube = \(2*\sqrt{2}\)
Answer is B. I din't understand the side of the second cube...how do you derive a side from the Total Surface Area???? TSA of cube = 6a^2 volume = a^3 so he started with volume = 1 ( a=1) then 6a^2 = 6 >>> first cube then second cube = double that so its 12 6a^2 = 12, a^2 = 2 >> a = root 2 volume of second cube = a^3 = root 2 cubed so that's 2 root 2
_________________
Click +1 Kudos if my post helped...
Amazing Free video explanation for all Quant questions from OG 13 and much more http://www.gmatquantum.com/og13th/
GMAT Prep software What if scenarios http://gmatclub.com/forum/gmatprepsoftwareanalysisandwhatifscenarios146146.html



Intern
Joined: 08 Jan 2013
Posts: 4

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
11 Jan 2013, 00:21
Given the volume of first cube V, the side of the cube is V raised to 1/3. Surface area of the first cube (4 * side ^2) will be 4*V raised to 2/3
Let the side of the second cube be x. Given the surface of the second cube is twice the surface area of the first cube, the surface area of the second cube can be expressed as
4 * x^2 = 2*4 V raised to 2/3
x^2 = 2 * V raised to 2/3
x = sqrt(2) * V raised to 1/3
volume of second cube will be x^3 = 2sqrt2 * V
So B is the answer
P.S. I interpreted surface area as the lateral surface area but not the total surface area; question would have specifically given if it was referring to total surface area and then the formula would have been 6 * side^2



Math Expert
Joined: 02 Sep 2009
Posts: 39744

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
11 Jan 2013, 04:46
4
This post received KUDOS
Expert's post
3
This post was BOOKMARKED



Senior Manager
Joined: 13 Aug 2012
Posts: 464
Concentration: Marketing, Finance
GPA: 3.23

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
11 Jan 2013, 05:14
2
This post received KUDOS
first cube: \(V = s^3\) \(SA = 6*s^2\) second cube: \(SA = 12*s^2\) get S: \(side = \sqrt{2} s\) \(V_2 = side ^ 3 = 2\sqrt{2}*s^3\) \(V_2 = 2\sqrt{2}V\) Answer: B
_________________
Impossible is nothing to God.



VP
Joined: 09 Jun 2010
Posts: 1418

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
24 Jan 2013, 08:24
gmat dose not test the remembering of formular. do not need formula s=Ar^2 we infer R=r. roor square of 2 V=Br^3 we infer the answer.
_________________
visit my facebook to help me. on facebook, my name is: thang thang thang



Intern
Joined: 14 May 2014
Posts: 45

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
21 May 2014, 09:54
Moving along with the question Volume of first Cube = V side = V^(1/3) surface area = 6* V^(2/3) Surface area of 2nd cube = 2* 6 * V^(2/3) = 12*V^(2/3) side = sqrt (surface area /6) =sqrt (2V^(2/3)) = sqrt(2) * V^(1/3) Volume = side^3 = [sqrt(2) * V^(1/3)]^3 = 2*sqrt(2)* V Answer is B
_________________
Help me with Kudos if it helped you "
Mathematics is a thought process.



SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1857
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
22 May 2014, 23:51
2
This post received KUDOS
First Cube detailsLet the side = a Volume \(V = a^3\) Surface area \(= a^2\) Second Cube detailsGiven that Surface area is twice \(= 2a^2\) It means each side is \(\sqrt{2}a\) So volume would be \(\sqrt{8} a^3 = 2\sqrt{2} . V\) Answer = B
_________________
Kindly press "+1 Kudos" to appreciate



GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16018

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
01 Jun 2015, 20:29
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.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources



GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16018

Re: If a certain cube has Volume V and a second cube has twice [#permalink]
Show Tags
16 Jul 2016, 03:06
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.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: If a certain cube has Volume V and a second cube has twice
[#permalink]
16 Jul 2016, 03:06







