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OG2015 PS In the rectangular solid

This topic has 1 expert reply and 0 member replies

OG2015 PS In the rectangular solid

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In the rectangular solid above, the three sides shown have areas 12, 15, and 20, respectively. What is the volume of the solid?

(A) 60
(B) 120
(C) 450
(D) 1,800
(E) 3,600

OA: A

Experts, please share an approach in solving this problem. Thank you.

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GMAT/MBA Expert

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lionsshare wrote:


In the rectangular solid above, the three sides shown have areas 12, 15, and 20, respectively. What is the volume of the solid?

(A) 60
(B) 120
(C) 450
(D) 1,800
(E) 3,600

OA: A
Let the dimensions (length, width and height) of the box be x, y and z
Volume = (length)(width)(height) = xyz
So, our GOAL is to find the value of xyz

The three sides shown have areas 12, 15, and 20, respectively
If one (rectangular) side has area 12, then we can say that xy = 12
If one (rectangular) side has area 15, then we can say that xz = 15
If one (rectangular) side has area 20, then we can say that yz = 20
[notice that we've accounted for all 3 dimensions]

Now, we'll apply the following property: If a = j, and b = k and c = l , then abc = jkl

So, we can write: (xy)(xz)(yz) = (12)(15)(20)
Simplify: x²y²z² = 3600
Rewrite left side as: (xyz)² = 3600
Take the square root of both sides to get: xyz = 60

So, the volume = 60

Answer: A
Cheers,
Brent

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Brent Hanneson – Creator of GMATPrepNow.com
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