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megafan
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While working alone at their respective constant rates, 09 Feb 2013, 14:37
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81% (01:45) correct 19% (02:02) wrong based on 268 sessions

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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
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C
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While working alone at their respective constant rates, 09 Feb 2013, 16:54
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megafan
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
Show more

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
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While working alone at their respective constant rates, 09 Feb 2013, 17:18
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hitman5532


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
Show more

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:
\(\frac{(4)(8)}{4+8}\) = \(2\frac{2}{3}\)
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While working alone at their respective constant rates, 09 Feb 2013, 17:50
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megafan
hitman5532


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:
\(\frac{(4)(8)}{4+8}\) = \(2\frac{2}{3}\)
Show more


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.
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While working alone at their respective constant rates, 10 Feb 2013, 02:10
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megafan
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
Show more

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?

(A) 22
(B) 25
(C) 28
(D) 32
(E) 56
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Discussed here: machine-a-produces-bolts-at-a-uniform-rate-of-120-every-143745.html
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While working alone at their respective constant rates, 12 Feb 2013, 00:27
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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
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While working alone at their respective constant rates, 29 Nov 2017, 07:39
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megafan
hitman5532


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:
\(\frac{(4)(8)}{4+8}\) = \(2\frac{2}{3}\)
Show more

megafan

please, what's the original formula?
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While working alone at their respective constant rates, 01 Dec 2017, 07:44
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megafan
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
Show more

The rate of X is 480/4 = 120 and the rate of Y is 480/8 = 60.

Since the combined rate is 180, it will take 480/180 = 48/18 = 8/3 = 2 2/3 hours = 2 hours and 40 minutes.

Answer: C
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While working alone at their respective constant rates, 08 Aug 2019, 02:07
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megafan
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
Show more
2x = y

3x are working, so 480:3=160min = 2h 40min
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While working alone at their respective constant rates, 11 Jul 2021, 11:30
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