Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 350,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

While working alone at their respective constant rates, [#permalink]
09 Feb 2013, 13:37

1

This post received KUDOS

00:00

A

B

C

D

E

Difficulty:

25% (medium)

Question Stats:

82% (02:28) correct
18% (01:34) wrong based on 73 sessions

While working alone at their respective constant rates, server X uploads 480 files in 4 hours and server Y uploads 480 files in 8 hours. If all files uploaded by these servers are the same size, how long would it take the two servers, working at the same time and at their respective constant rates, to process a total of 480 files?

(A) 2 hr (B) 2hr 20 min (C) 2hr 40 min (D) 5 hr 40 min (E) 6hr

Re: While working alone at their respective constant rates, [#permalink]
09 Feb 2013, 15:54

megafan wrote:

While working alone at their respective constant rates, server X uploads 480 files in 4 hours and server Y uploads 480 files in 8 hours. If all files uploaded by these servers are the same size, how long would it take the two servers, working at the same time and at their respective constant rates, to process a total of 480 files?

(A) 2 hr (B) 2hr 20 min (C) 2hr 40 min (D) 5 hr 40 min (E) 6hr

Source: Gmat Hacks 1800

Server X processes 480/4 files per hour = 120 per hour Server Y processes 180/8 files per hour = 60 per hour Total files processed per hour when X and Y work together = 120+60 per hour = 180 files per hour

Re: While working alone at their respective constant rates, [#permalink]
09 Feb 2013, 16:18

hitman5532 wrote:

Server X processes 480/4 files per hour = 120 per hour Server Y processes 180/8 files per hour = 60 per hour Total files processed per hour when X and Y work together = 120+60 per hour = 180 files per hour

480/180 = 2 2/3 hours

While this is good, there is a faster way to do this—If you realize that the # of files is the same. Then you just use the combined rate formula: \(\frac{(4)(8)}{4+8}\) = \(2\frac{2}{3}\) _________________

Re: While working alone at their respective constant rates, [#permalink]
09 Feb 2013, 16:50

megafan wrote:

hitman5532 wrote:

Server X processes 480/4 files per hour = 120 per hour Server Y processes 180/8 files per hour = 60 per hour Total files processed per hour when X and Y work together = 120+60 per hour = 180 files per hour

480/180 = 2 2/3 hours

While this is good, there is a faster way to do this—If you realize that the # of files is the same. Then you just use the combined rate formula: \(\frac{(4)(8)}{4+8}\) = \(2\frac{2}{3}\)

If the numbers were more odd/complex the formula always helps me, I did the other way in my head in about 8 seconds because the numbers are simple.

Re: While working alone at their respective constant rates, [#permalink]
10 Feb 2013, 01:10

Expert's post

megafan wrote:

While working alone at their respective constant rates, server X uploads 480 files in 4 hours and server Y uploads 480 files in 8 hours. If all files uploaded by these servers are the same size, how long would it take the two servers, working at the same time and at their respective constant rates, to process a total of 480 files?

(A) 2 hr (B) 2hr 20 min (C) 2hr 40 min (D) 5 hr 40 min (E) 6hr

Source: Gmat Hacks 1800

Original question is from OG:

Quote:

Machine A produces bolts at a uniform rate of 120 every 40 seconds, and Machine B produces bolts at a uniform rate of 100 every 20 seconds. If the two machines run simultaneously, how many seconds will it take for them to produce a total of 200 bolts?

Re: While working alone at their respective constant rates, [#permalink]
11 Feb 2013, 23:27

Server X : Work done in 1 hour is =1/4 Server Y : Work done in 1 hour is = 1/8 Work done by X and Y togather in 1 hour = 1/4+1/8= 6/16 Hence time required to complete upload= 16/6 hours = 2 hour 40 min. Hence option C

gmatclubot

Re: While working alone at their respective constant rates,
[#permalink]
11 Feb 2013, 23:27

Back to hometown after a short trip to New Delhi for my visa appointment. Whoever tells you that the toughest part gets over once you get an admit is...