Register    Login    Search    Rss Feeds

Forums Home » Ask An Instructor » GMAT Math » GMAT Prep Math


 Page 1 of 1 [ 3 posts ] 



  Print view Print view Previous topic Previous topic | Next topic Next topic
 

Company C has a machine

Author Message
candace_washington1980
 Post subject: Company C has a machine
 Post Posted: Thu Aug 06, 2009 4:42 am 
Offline
Forum Guests


Posts: 17
Hi I,m new this website, I have several questions from the gmat test prep that I'm having difficulty with. I was able to get this one correct but I'm not sure how I got it. Please help.

Company C has a machine that, working alone at its constant rate, processes 100 units of a certain product in 5 hours. If Company C plans to buy a new machine that will process this product at a constant rate and if the two machines, working together at their respective constant rates, are to process 100 units of this product in 2 hours, what should be the constant rate, in units per hour, of the new machine?

A. 50
B. 45
C. 30
D. 25
E. 20

The answer is C, but how?
Top 
furtadovinod
 Post subject: Re: Company C has a machine
 Post Posted: Thu Aug 06, 2009 11:18 am 
Offline
Students


Posts: 28
candace_washington1980 wrote:
Hi I,m new this website, I have several questions from the gmat test prep that I'm having difficulty with. I was able to get this one correct but I'm not sure how I got it. Please help.

Company C has a machine that, working alone at its constant rate, processes 100 units of a certain product in 5 hours. If Company C plans to buy a new machine that will process this product at a constant rate and if the two machines, working together at their respective constant rates, are to process 100 units of this product in 2 hours, what should be the constant rate, in units per hour, of the new machine?

A. 50
B. 45
C. 30
D. 25
E. 20

The answer is C, but how?


I guess there are number of ways to work this out. My way is

Old machine processes 100 units of the product in 5 hrs.

Therefore, it produces 20 units per hr.

Old machine + New machine must produce 100 units in 2 hrs.
Therefore, 50 units per hr.

Since old machine produces 20 units per hr, the new machine must produce at 30 units per hr to get a total of 20+30=50 units per hr.
Top 
candace_washington1980
 Post subject: Re: Company C has a machine
 Post Posted: Thu Aug 06, 2009 12:24 pm 
Offline
Forum Guests


Posts: 17
Well this is how I worked it.

Machine 1 Machine 2 Both machines
rate=100 x rate=100
5 2
rate= 20 rate= 50

20 + x = 50
x = 30

Is this correct or did I get lucky because the numbers worked out?
Top 
Display posts from previous:  Sort by  
 
 Page 1 of 1 [ 3 posts ] 





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: