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Math Expert
Joined: 02 Sep 2009
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Question Stats:
49% (03:34) correct 51% (03:12) wrong based on 99 sessions
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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
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Re M0535
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16 Sep 2014, 00:26
Official Solution: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 To find the total cost of copying 1,200 pages, we need to know: 1. How long it takes for an attendant to copy 1,200 pages on each copier. 2. How much it costs per job on each of the machines. Cost of Time: A \(\frac{1200}{12} = 100\) mins (exact) costs: $60 B \(\frac{1200}{7} = 170\) mins (approx) costs: $90 C \(\frac{1200}{19} = 63\) mins (approx) costs: $60 Price per Job: A \(1200*$0.08=$96\) B \(1200*$0.05=$60\) C \(1200*$0.11=$132\) Total cost including attendant's pay: A \(96+60 = 156\) B \(60+90 = 150\) C \(132+60 = 192\) The best choice is Copier B. Answer: B
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Re: M0535
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16 Jan 2015, 12:13
Hi Bunuel,
In this case...we figured out the costs associated with the individual printers, and that itself took some time. What about options D and E? are there some generalizations regarding the rate of 2 workers together such as: unless the rate of 2 workers together working together is more than double the rate of any of the individuals....they are better off working alone? would this be a fair generalization?
Thanks,



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Re: M0535
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21 Aug 2015, 13:01
amishra1 wrote: Hi Bunuel,
In this case...we figured out the costs associated with the individual printers, and that itself took some time. What about options D and E? are there some generalizations regarding the rate of 2 workers together such as: unless the rate of 2 workers together working together is more than double the rate of any of the individuals....they are better off working alone? would this be a fair generalization?
Thanks, You can eliminate D and E immediately because the question asks "which copier alone will be the most efficient choice to make 1,200 copies?" This problem is not difficult to understand. However, you have to recognize that it will be very time consuming. Depending on where you are at on the test(in terms of the time you have left and your mental state), you might need to make a random guess among A, B, and C to move on.



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Re: M0535
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20 Oct 2015, 03:09
Hi Bunnel,
I didnt get how yoy got $90 for 170min? can you please explain me to clear my doubt?



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Re: M0535
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12 Nov 2015, 22:41
I don't get why this problem is 95% hard rated. "Alone" eliminates right away D and E. Machine C is way too slow and expensive so choice C out. You can spend a minute and calculate to rule out whether B or A however at short reasoning B looks preferable. Why? Because it is faster when the time matters  attendat gets paid for the time spent and every additional minute could count. Although B is more costly in terms of $/1 page  in time constraints I would bet on B without calculation and continue.
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Re: M0535
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26 May 2016, 02:48
chaitanyakankanaka wrote: Hi Bunnel,
I didnt get how yoy got $90 for 170min? can you please explain me to clear my doubt? chaitanyakankanaka: Every 60mins the attendant get $30, next min he'll get extra $30 (cost@60mins = $30, cost@61mins = 30 + 30 = $60) So, 170mins = 60m + 60m + 50m = 30 + 30 + 30 = $90.
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Re: M0535
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10 Feb 2017, 04:23
shasadou wrote: I don't get why this problem is 95% hard rated. "Alone" eliminates right away D and E. Machine C is way too slow and expensive so choice C out. You can spend a minute and calculate to rule out whether B or A however at short reasoning B looks preferable.
Why? Because it is faster when the time matters  attendat gets paid for the time spent and every additional minute could count. Although B is more costly in terms of $/1 page  in time constraints I would bet on B without calculation and continue. Why is Machine C way too slow ? I think it's the fastest one with 19 copies per minute ...



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Re: M0535
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30 Sep 2017, 13:44
1200/19 is approximately 63 not approximately 61. Also, to be more GMAT like, it should be explicitly stated that rate units stay the same the whole time. Other than that, good question and one that really tests how quickly you can do arithmetic.



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Re: M0535
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01 Oct 2017, 04:53
grassmonkey wrote: 1200/19 is approximately 63 not approximately 61. Also, to be more GMAT like, it should be explicitly stated that rate units stay the same the whole time. Other than that, good question and one that really tests how quickly you can do arithmetic. _______________ Edited. Thank you.
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Re: M0535
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24 Mar 2019, 06:37
Bunuel wrote: Official Solution:
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
To find the total cost of copying 1,200 pages, we need to know: 1. How long it takes for an attendant to copy 1,200 pages on each copier. 2. How much it costs per job on each of the machines. Cost of Time: A \(\frac{1200}{12} = 100\) mins (exact) costs: $60 B \(\frac{1200}{7} = 170\) mins (approx) costs: $90 C \(\frac{1200}{19} = 63\) mins (approx) costs: $60 Price per Job: A \(1200*$0.08=$96\) B \(1200*$0.05=$60\) C \(1200*$0.11=$132\) Total cost including attendant's pay: A \(96+60 = 156\) B \(60+90 = 150\) C \(132+60 = 192\) The best choice is Copier B.
Answer: B Hi BunuelHow did you calculate for Copier A, how did you calculate cost of time = $60? Similarly, for Copier B, how did you calculate cost of time = $90? Kindly please explain?? Thanks Would really appreciate your help!



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Re: M0535
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24 Mar 2019, 07:38
JIAA wrote: Bunuel wrote: Official Solution:
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
To find the total cost of copying 1,200 pages, we need to know: 1. How long it takes for an attendant to copy 1,200 pages on each copier. 2. How much it costs per job on each of the machines. Cost of Time: A \(\frac{1200}{12} = 100\) mins (exact) costs: $60 B \(\frac{1200}{7} = 170\) mins (approx) costs: $90 C \(\frac{1200}{19} = 63\) mins (approx) costs: $60 Price per Job: A \(1200*$0.08=$96\) B \(1200*$0.05=$60\) C \(1200*$0.11=$132\) Total cost including attendant's pay: A \(96+60 = 156\) B \(60+90 = 150\) C \(132+60 = 192\) The best choice is Copier B.
Answer: B Hi BunuelHow did you calculate for Copier A, how did you calculate cost of time = $60? Similarly, for Copier B, how did you calculate cost of time = $90? Kindly please explain?? Thanks Would really appreciate your help! Check here: https://gmatclub.com/forum/threecopym ... 60805.htmlHope it helps.
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