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Working at their respective constant rates, machine A makes 100 copies

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Ryerson (Ted Rogers) Thread Master
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Working at their respective constant rates, machine A makes 100 copies  [#permalink]

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New post 23 Dec 2015, 08:52
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A
B
C
D
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Difficulty:

  5% (low)

Question Stats:

92% (01:26) correct 8% (02:04) wrong based on 224 sessions

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Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 150 copies in 10 minutes. If these machines work simultaneously at their respective rates for 30 minutes, what is the total number of copies that they will produce?

(A) 250
(B) 425
(C) 675
(D) 700
(E) 750

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Re: Working at their respective constant rates, machine A makes 100 copies  [#permalink]

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New post 26 Dec 2015, 09:57
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Hi All,

This question is essentially just about the two rates involved; as such, the math can be done in a variety of ways (depending on how you want to organize the information).

We're given the rates of 2 machines:
1) Machine A makes 100 copies in 12 minutes
2) Machine B makes 150 copies in 10 minutes.

We're asked for the total number of copies that the two machines will produce in 30 minutes.

30 minutes/12 minutes = 2.5 'sets' of 100 copies
30 minutes/10 minutes = 3 'sets' of 150 copies

(2.5)(100) + 3(150) =
250 + 450 =
700 copies

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Re: Working at their respective constant rates, machine A makes 100 copies  [#permalink]

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New post 21 Jul 2016, 07:38
rate a= 100/12 copy/min = 25/3 copy/min
rate b = 150/10 copy/min = 15 copy/min

rate a + rate b = rate(ab)

now work done tog = rate(ab) * time ---> (work tog for 30 mins)
work = (25+45)/3 * 30 = 700 copies
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Re: Working at their respective constant rates, machine A makes 100 copies  [#permalink]

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New post 21 Jul 2016, 08:47
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RSOHAL wrote:
Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 150 copies in 10 minutes. If these machines work simultaneously at their respective rates for 30 minutes, what is the total number of copies that they will produce?

(A) 250
(B) 425
(C) 675
(D) 700
(E) 750


Machine A can produce 100 *30/12= 250 copies

And, Machine B can produce 150* 30/10= 450 Copies

Total producing 700 Copies.

D is the answer
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Re: Working at their respective constant rates, machine A makes 100 copies  [#permalink]

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New post 30 Sep 2018, 10:36
RSOHAL wrote:
Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 150 copies in 10 minutes. If these machines work simultaneously at their respective rates for 30 minutes, what is the total number of copies that they will produce?

(A) 250
(B) 425
(C) 675
(D) 700
(E) 750


A makes in 12 min 100 copies..so in 1 min it makes 25/3 copies
B makes in 10 min 150 copies..so in 1 min it makes 15 copies

So working together A+B in 1 min makes = 25/3+15 = 70/3 copies

So in 30 min they will make = 30*70/3=700 copies so ans is D
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Re: Working at their respective constant rates, machine A makes 100 copies   [#permalink] 30 Sep 2018, 10:36
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