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A copy machine, working at a constant rate, makes 35 copies

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shradhagrover18
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A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   25 Jun 2012, 09:32
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A copy machine, working at a constant rate, makes 35 copies per minute. A second copy machine, working at a constant rate, makes 55 copies per minute. Working together at their respective rates, how many copies do the two machines make in half an hour ?

A. 90
B. 2,700
C. 4,500
D. 5,400
E. 324,000
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B
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Bunuel
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   25 Jun 2012, 09:48
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A copy machine, working at a constant rate, makes 35 copies per minute. A second copy machine, working at a constant rate, makes 55 copies per minute. Working together at their respective rates, how many copies do the two machines make in half an hour ?

A. 90
B. 2,700
C. 4,500
D. 5,400
E. 324,000

Together the two machines make 35+55=90 copies per minute. So, in half an hour they will make 90*30=2,700 copies.

Answer: B.
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mbaiseasy
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   15 Nov 2012, 00:59
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\(Rate1+Rate2=CombinedRate\)
\(\frac{35}{1min}+\frac{55}{1min}=\frac{90}{1min}\)
\(\frac{90}{1min}(30min)=2,700\)copies

Answer:B
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   30 Apr 2013, 00:50
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shahebali wrote:
why not 1/35 + 1/55 = 18/385 for 2 copies?


1/35 minutes is the time the first machine needs to make one copy.
1/55 minutes is the time the second machine needs to make one copy.

Why are you adding them?
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   06 Aug 2019, 11:06
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Combined Rate per minute = 35 + 55
So, in 30 min, work done = 90*30 = 2700
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   30 Apr 2013, 00:01
why not 1/35 + 1/55 = 18/385 for 2 copies?
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   07 May 2013, 16:09
darn did something stupid
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PKPKay
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   05 Jun 2013, 16:37
Machine A = 35 copies per minute. 35*30 = 1050 copies in 30 minutes
Machine B = 55 copies per minute. 55*30 = 1650 copies in 30 minutes
1050+1650 = 2700 copies in 30 mins
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   07 Feb 2017, 02:17
Simple conception of work problem. If A makes 35/copies/min B makes 65/copies/min. Together each working independently they make 90 copies/min. Multiply 90 copies by 30 minutes to give you 2700 copies a minute.
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   27 May 2017, 06:23
shradhagrover18 wrote:
A copy machine, working at a constant rate, makes 35 copies per minute. A second copy machine, working at a constant rate, makes 55 copies per minute. Working together at their respective rates, how many copies do the two machines make in half an hour ?

A. 90
B. 2,700
C. 4,500
D. 5,400
E. 324,000


1st Copy machine's Rate, A = 35 copies per minute
2nd Copy Machine's Rate, B = 55 copies per minute

Working Together, means we can ADD THE RATES
Combined Rate, A+B= 35 + 55= 90 copies per minute
i.e 1 minute = 90 copies
or, 30 minutes (half an hour) =90 x 30 copies = 2700 Copies

Hence, Answer is:
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B
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   27 May 2017, 08:40
shradhagrover18 wrote:
A copy machine, working at a constant rate, makes 35 copies per minute. A second copy machine, working at a constant rate, makes 55 copies per minute. Working together at their respective rates, how many copies do the two machines make in half an hour ?

A. 90
B. 2,700
C. 4,500
D. 5,400
E. 324,000


\((35+55)*30 = 2700\)

Thus, the correct answer will be (B)
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   29 Jun 2021, 04:52
To find the combined rate of the two machines, add their individual rates:
35 copies/minute + 55 copies/minute = 90 copies/minute.
The question asks how many copies the machines make in half an hour, or 30
minutes.
90 copies/minute × 30 minutes = 2,700 copies.
The correct answer is B.
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   01 Sep 2022, 10:19
shradhagrover18 wrote:
A copy machine, working at a constant rate, makes 35 copies per minute. A second copy machine, working at a constant rate, makes 55 copies per minute. Working together at their respective rates, how many copies do the two machines make in half an hour ?

A. 90
B. 2,700
C. 4,500
D. 5,400
E. 324,000


Together they copy (35+55) in 1 minute
So in 30 minute 30*90 copies
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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink] New post   11 Dec 2023, 11:01
shahebali wrote:
why not 1/35 + 1/55 = 18/385 for 2 copies?

As the rate are same, you dont need to think like that.

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Re: A copy machine, working at a constant rate, makes 35 copies [#permalink]
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