gmat preparation courses

It is currently Mon Jun 18, 2018 10:53 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 2 posts ] 
Author Message
 Post subject: GMAT Rate
PostPosted: Thu Jan 24, 2013 3:55 pm 
Offline

Joined: Sun May 30, 2010 2:23 am
Posts: 498
Joe is painting a rectangular room whose dimensions are given by a, b and c meters. Joe takes 8 hours to paint a wall with dimensions a and c. He takes 4 hours to paint a wall with dimensions b and c and 12 hours to paint the ceiling with dimensions a and b. If Joe works at a constant rate and a = 6, then what is the volume of the room?

A. 18 cubic meters
B. 24 cubic meters
C. 30 cubic meters
D. 36 cubic meters
E. It can’t be determined.

(D) This is a typical work problem with an addition, finding the volume. Start by finding the area of the two walls and the ceiling.

Wall 1 has the area ac, and it took 8 hours to paint it. So the area Joe paints in one hour is (ac)/8.

Wall 2 has area bc, and took 4 hours to paint. So the area Joe paints in one hour is (bc)/4.

The ceiling has the area ab, and it took 12 hours to paint it. So the area Joe paints in one hour is (ab)/12.

Since Joe is working at a constant rate, the area painted in one hour is the same. So (bc)/4 = (ab)/12 .

Since a = 6, (bc)/4 = (6b)/12 .

So c = 4 × 6 / 12 .

c = 2

(ac)/8 = (bc)/4, where a = 6 and c = 2. So (6 × 2)/8 = (b × 2)/4.

b = 3

This gives a = 6 meters, b = 3 meters, and c = 2 meters. The volume of the room is a × b × c = 6 × 3 × 2 = 36 cubic meters.

So the correct answer is choice (D).


Top
 Profile  
 
 Post subject: Re: GMAT Rate
PostPosted: Thu Jan 24, 2013 4:01 pm 
Offline

Joined: Thu Dec 06, 2012 5:19 pm
Posts: 9
woah good prob. threw me off when i read it for the first time...


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group