The shaded face of cube C, shown here, has an area...

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BTGmoderatorLU: Moderator; Posts: 2554; Joined: Sun Oct 15, 2017 1:50 pmFollowed by: 6 members

by BTGmoderatorLU » Tue Dec 26, 2017 3:13 pm

The shaded face of cube C, shown here, has an area of 49 squares inches. What is the volume of Cube C in cubic inches?

A. 7
B. 28
C. 84
D. 343
E. 364

The OA is D.

I'm confused with this PS question, can I say that L^2=49 and then the volume of C=7^3=343?

Experts, any suggestion? Thanks in advance.

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Source: Beat The GMAT — Problem Solving | Tue Dec 26, 2017 3:13 pm

elias.latour.apex: Master | Next Rank: 500 Posts; Posts: 228; Joined: Thu Apr 20, 2017 1:02 amFollowed by: 3 members; Location: Global; Thanked: 32 times; GMAT Score:770

A simple solution path

by elias.latour.apex » Wed Dec 27, 2017 4:45 am

Since it is a cube, all sides of the cube are equal.
Since the area of one face is 49, each side must be 7.
Therefore, the volume of the cube will be 49x7, which is the same as 7^3.

Since the units digit of the answer will be a 3, and since only answer choice D fits that criterion, it is not necessary to do all the math.

Elias Latour
Verbal Specialist @ ApexGMAT
blog.apexgmat.com
+1 (646) 736-7622

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Scott@TargetTestPrep: GMAT Instructor; Posts: 8152; Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members; Location: Los Angeles, CA; Thanked: 43 times

by Scott@TargetTestPrep » Wed Sep 04, 2019 5:21 pm

BTGmoderatorLU wrote:

The shaded face of cube C, shown here, has an area of 49 squares inches. What is the volume of Cube C in cubic inches?

A. 7
B. 28
C. 84
D. 343
E. 364

The OA is D.

I'm confused with this PS question, can I say that L^2=49 and then the volume of C=7^3=343?

Experts, any suggestion? Thanks in advance.

Since each side of the cube is 7 inches, the volume is 7 x 7 x 7 = 343 cubic inches.

Answer: D

Scott Woodbury-Stewart
Founder and CEO
[email protected]

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