Three copy machines are making copies of the same document.

We need to find whether the cost differential per copy is enough to offset the speed differential (because of which the attendant needs to be paid more/less)
Copier A - 8 cents
Copier B - 5 cents
Copier C - 11 cents

For 1200 pages, copier B will cost 3 cents *1200 = $36 less than copier A and copier C will cost $36 more than copier A.

Copier A takes 1200/12 = 100 min i.e. 1 hr 40 mins to print 1200 copies. $60 is paid to attendant.
Copier B takes 1200/7 = 170 min i.e. less than 3 hrs to print 1200 copies. $90 is paid to attendant.
Copier C takes 1200/19 = 63 min i.e. $60 is paid to attendant.

Copier B is the most efficient since it costs $36 less to print but $30 more to pay the attendant so overall, it costs $6 less than copier A. (Copier C is most expensive)

Answer (B)
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Hi Guerro 25,

Answer should be B

Here is my solution

Given A =12 copies per minute so 100 min for 1200 copies . Total Cost will be = 1200*8=9600 cents or $96 + $ 60 for worker = $156
B = 7 copies per minute so ~171 minutes for 1200 copies. total cost will be 5*1200= 6000 cents or 60$ + worker charge $90 = $150
C= 19 copies per minute so about 63 minutes for 1200 copies. Total cost will be 11*1200= 13200 or $ 132 + $ 60= $ 192

God knows when I will stop making silly mistakes...While calculating for B originally I took rate as $60 per hour (Exclusively for B ) and ended up marking A.
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I dont understand why for example copier A get 60$ with 1 hr 40 mins, it is supposed to be $30 + (40/60)*30, could anybody please explain this point to me I still do not get it ! many thanks !

Hi All,

While I agree with the correct answer, I'm curious about the source of this question. Does anyone know it?

The question asks "which copier ALONE would be the most efficient choice...", but two of the answer choices do NOT fit the "format" of what is asked (they include 2 COPIERS).

GMAT assassins aren't born, they're made,
Rich
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Printing cost for
A: 1200*0.08 = 96
B: 1200*0.05 =60
C: 1200*0.11 = 132

Based on time consuming, attendance hiring cost for
A: 2*30 = 60 (100minutes, about 2 hours)
B: 3*30 = 90 (172 minutes, about 3 hours)
C: 2*30 = 60 (64 minutes, about 2 hours)

Total cost for
A: 96+60 = 156
B: 60+90 = 150
C: 132+60 = 192

Correct answer is B

Slash-and-burn ....

You probably ignored the bracket part of the question:

"If a separate attendant has to be hired for each copier and be paid $30 per hour (you have to pay $60 if the attendant works for one hour and one minute)

Even if the attendant works for a minute more, he has to be paid for the full hour. So for 1 hr 40 mins, he needs to be paid for 2 hrs i.e. $60.
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Three copy machines are making copies of the same document. Copier A makes 12 copies per minute, Copier B makes 7, and Copier C makes 19. It costs 8 cents/copy for Copier A, 5 cents/copy for Copier B, and 11 cents/copy for Copier C. If a separate attendant has to be hired for each copier and be paid $30 per hour (you have to pay $60 if the attendant works for one hour and one minute), which copier alone will be the most efficient choice to make 1,200 copies?

A)Copier A
b)Copier B
c)Copier C
d)A and B
e)A and C

A = (1200/12) = 100 (2 hrs)
amount = (2*30)+(8*1200)/100 = 60+96 = 156

B = (1200/7) = 171.XX = 180 (3 hrs)
amount = (3*30)+(1200*5)/100 = 90+60 = 150

C = (1200/19) = 63.XX = 64 (2 hrs)
amount = (2*30)+(1200*11)/100 = 60+132 = 192

Answer B

Hi,

I have serious doubts this question can be answered in less than 2 minutes, it already takes 35 seconds to be read. Does anyone manage to do it that quickly?

Hi PaulFrederick,

Not every question in the Quant section is supposed to be answered in under 2 minutes. Certain questions take far less time while others take more time. The idea that you should spend 2 minutes (or less) on each question is silly. Your goal should be to approach each prompt in an efficient way.

Wordy questions are not necessarily hard questions, but you have to acknowledge that since it will take longer to read this prompt than 'normal', you will end up using a lot of time if you have to read it over and over again. So what work can YOU do to avoid having to reread it repeatedly?

GMAT assassins aren't born, they're made,
Rich
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Most, if not all, Quant PS GMAT questions can be solved in much less than 2 mins. The questions are logical puzzles, not cumbersome to do and will involve a trick or two. You can actually run through the Quant questions at an average speed of a question a minute. Still, most people utilize the 75 mins or even run out of time because they either take a very long method, or get stuck with wrong logic or take too much time to figure out the trick or their mind wanders. The process involved will never be time consuming - figuring out the process might be. Even if you take an extra 15 secs to read the question stem in a particular question, it shouldn't affect anything.

Request you to check out my solution above. The calculations involved are minimal and easy to do. There are no equations to be solved. The only thing that one has to be careful with in a question like this is 'be neat with his/her work'. When I calculate the differential cost, I need to remember that this is differential of B and A. When I calculate wages of the attendant, I need to label A/B/C as the case may be so that I don't mess up. Of course, you cannot lose focus midway but that is true for every question.
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Copier A --> attendant needed for 2hrs @ $30/hr + $96 for copies = $156

Copier B --> attendant needed for 3hrs @ $30/hr + $60 for copies = $150

Copier C --> attendant needed for 2 hrs @ $30/hr + $60 for copies = $192

B is the most efficient printer.

1200/12 = 100 => so for Copier A, an attendant is needed for 2hrs @ $30/hr + $96 for copies = $156
1200/7 = 172 => so for Copier B, an attendant is needed for 3hrs @ $30/hr + $60 for copies = $150
1200/19 = 100 => so for Copier c, an attendant is needed for 2 hrs @ $30/hr + $60 for copies = $192

B is the most efficient printer

Hello there?

At first even I couldn't figure out whether $60 is for 1 hour and 1 min or it should be like even a single minute beyond every hour, attendant will be paid hourly rate that is $30.

In my view, such contradictory languages are not used in actual GMAT. Above statement can be made more clear and having only one meaning.

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