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Math Expert V
Joined: 02 Sep 2009
Posts: 53831
If the length of an edge of cube X is twice the length of an  [#permalink]

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3
5 00:00

Difficulty:   5% (low)

Question Stats: 88% (00:45) correct 12% (01:05) wrong based on 611 sessions

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The Official Guide For GMAT® Quantitative Review, 2ND Edition

If the length of an edge of cube X is twice the length of an edge of cube Y, what is the ratio of the volume of cube Y to the volume of cube X?

(A) 1/2
(B) 1/4
(C) 1/6
(D) 1/8
(E) 1/27

Problem Solving
Question: 139
Category: Geometry Volume
Page: 80
Difficulty: 550

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Math Expert V
Joined: 02 Sep 2009
Posts: 53831
Re: If the length of an edge of cube X is twice the length of an  [#permalink]

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SOLUTION

If the length of an edge of cube X is twice the length of an edge of cube Y, what is the ratio of the volume of cube Y to the volume of cube X?

(A) 1/2
(B) 1/4
(C) 1/6
(D) 1/8
(E) 1/27

The length of cube Y = 1;
The length of cube X = 2;

The ratio of the volume of cube Y to the volume of cube X = 1^3/2^3 = 1/8.

_________________
Manager  Joined: 04 Jan 2014
Posts: 117
GMAT 1: 660 Q48 V32 GMAT 2: 630 Q48 V28 GMAT 3: 680 Q48 V35 Re: If the length of an edge of cube X is twice the length of an  [#permalink]

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1
1
Let Y's edge be a. Then X's edge is 2a.

Y's volume = a^3
X's volume = (2a)^3 = 8(a^3)

Ratio Y's volume to X's volume = 1/8

Manager  Joined: 20 Dec 2013
Posts: 229
Location: India
Re: If the length of an edge of cube X is twice the length of an  [#permalink]

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1
Option D.
Let side of X=2
Side of Y=1
Volume of cube=(side)^3
Vol. Y=1
Vol. X=8
Ratio=1/8

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Director  G
Joined: 24 Nov 2015
Posts: 502
Location: United States (LA)
Re: If the length of an edge of cube X is twice the length of an  [#permalink]

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Consider side(edge) of cube Y as 1 and side(edge) of cube X as 2
Volume of cube Y = $$1^3$$ = 1
Volume of cube X = $$2^3$$ = 8
Ratio = $$\frac{1}{8}$$

Correct Answer - D
Senior DS Moderator V
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Concentration: International Business, General Management
GPA: 3.64
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Re: If the length of an edge of cube X is twice the length of an edge of  [#permalink]

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length of edge of cube x = 2a
length of edge of cube y = a

Ratio of volume y / volume x = {(length of edge of cube y)/(length of edge of cube x)}^3 = 1/8 . Hence answer is D.
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Status: QA & VA Forum Moderator
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Re: If the length of an edge of cube X is twice the length of an edge of  [#permalink]

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Bunuel wrote:
If the length of an edge of cube X is twice the length of an edge of cube Y, what is the ratio of the volume of cube Y to the volume of cube X?

(A) 1/2
(B) 1/4
(C) 1/6
(D) 1/8
(E) 1/27

Let Length of edge of cube Y be 1, so edge of cube X is 2
Volume of Cube Y = 1 & Volume of Cube X = 8

So,ratio of the volume of cube Y to the volume of cube X is $$\frac{1}{8}$$, thus answer will be (D)

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Board of Directors P
Status: QA & VA Forum Moderator
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GPA: 3.5
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Re: If the length of an edge of cube X is twice the length of an edge of  [#permalink]

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Bunuel wrote:
If the length of an edge of cube X is twice the length of an edge of cube Y, what is the ratio of the volume of cube Y to the volume of cube X?

(A) 1/2
(B) 1/4
(C) 1/6
(D) 1/8
(E) 1/27

Let Length of edge of cube Y be 1, so edge of cube X is 2
Volume of Cube Y = 1 & Volume of Cube X = 8

So,ratio of the volume of cube Y to the volume of cube X is $$\frac{1}{8}$$, thus answer will be (D)

_________________
Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )
Intern  B
Joined: 20 Aug 2016
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Location: India
Concentration: Strategy, International Business
WE: Operations (Computer Software)
Re: If the length of an edge of cube X is twice the length of an edge of  [#permalink]

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Let the edge of Cube Y = p
so as per the question the edge of Cube X = 2p

as we know the edge of cube Y is p so its volume is = p^3
similarly as we know the edge of cube X is 2p so its volume is = (2p)^3 = 8p^3

so what is asked in the question is the ratio of Volume of cube Y to Volume of cube X that is = (p^3/8p^3) ---> 1/8

So answer is D.

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Re: If the length of an edge of cube X is twice the length of an  [#permalink]

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_________________ Re: If the length of an edge of cube X is twice the length of an   [#permalink] 23 Aug 2018, 02:05
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# If the length of an edge of cube X is twice the length of an

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