A certain clay cube has volume 64 cubic inches

Expert replies

SpencerP: Newbie | Next Rank: 10 Posts; Posts: 3; Joined: Thu Nov 20, 2014 5:33 pm

by SpencerP » Thu Aug 20, 2015 10:43 am

A certain clay cube has volume 64 cubic inches. If a smaller clay cube is formed and has half the volume of the original cube, how many inches long is an edge of the smaller cube?

A) 2
B) 4
C) 8
D) 4^1/3
E) 2 4^1/3

Correct Answer: E

Like this post

Source: Beat The GMAT — Problem Solving | Thu Aug 20, 2015 10:43 am

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Thu Aug 20, 2015 10:51 am

SpencerP wrote:A certain clay cube has volume 64 cubic inches. If a smaller clay cube is formed and has half the volume of the original cube, how many inches long is an edge of the smaller cube?

A) 2
B) 4
C) 8
D) âˆ›4
E) 2âˆ›4

When posting questions, please use the spoiler function to hide the correct answer. This will allow others to attempt the question without seeing the final answer.

Volume of smaller cube is HALF of original cube.
So, volume of smaller cube = (1/2)(64) = 32

Volume of cube = (length of one side)Â³ [aside: edge is the same as side]
So, (length of one side)Â³ = 32
This means length of one side = âˆ›32

None of the answer choices matches this, so we must simplify âˆ›32
âˆ›32 = âˆ›(8 x 4)
= (âˆ›8)(âˆ›4)
= [spoiler]2âˆ›4[/spoiler]
= E

Brent Hanneson - Creator of GMATPrepNow.com

Like this post

Max@Math Revolution: Elite Legendary Member; Posts: 3991; Joined: Fri Jul 24, 2015 2:28 amFollowed by: 37 members; Location: Las Vegas, USA; Thanked: 19 times

by Max@Math Revolution » Fri Aug 21, 2015 7:05 pm

Forget conventional ways of solving math questions. In PS, IVY approach is the easiest and quickest way to find the answer.

A certain clay cube has volume 64 cubic inches. If a smaller clay cube is formed and has half the volume of the original cube, how many inches long is an edge of the smaller cube?

A) 2
B) 4
C) 8
D) 4^1/3
E) 2 4^1/3

Correct Answer: E

==> Since the new cube has half the volume of the original cube, assuming the individual side of the cube has length a, a^3=64/2=32.

a=(32)^1/3, (2^3*2^2)^1/3=2(2^2)^1/3=2(4)^1/3, therefore E is the answer.

www.mathrevolution.com
l The one-and-only World's First Variable Approach for DS and IVY Approach for PS that allow anyone to easily solve GMAT math questions.

l The easy-to-use solutions. Math skills are totally irrelevant. Forget conventional ways of solving math questions.

l The most effective time management for GMAT math to date allowing you to solve 37 questions with 10 minutes to spare

l Hitting a score of 45 is very easy and points and 49-51 is also doable.

l Unlimited Access to over 120 free video lessons at https://www.mathrevolution.com/gmat/lesson

Our advertising video at https://www.youtube.com/watch?v=R_Fki3_2vO8

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

559 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review