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M05-35

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Math Expert
Joined: 02 Sep 2009
Posts: 42302

Kudos [?]: 133014 [0], given: 12402

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16 Sep 2014, 00:26
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Difficulty:

95% (hard)

Question Stats:

46% (02:36) correct 54% (02:31) wrong based on 141 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
[Reveal] Spoiler: OA

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Kudos [?]: 133014 [0], given: 12402

Math Expert
Joined: 02 Sep 2009
Posts: 42302

Kudos [?]: 133014 [1], given: 12402

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16 Sep 2014, 00:26
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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 _________________ Kudos [?]: 133014 [1], given: 12402 Intern Joined: 11 Jan 2013 Posts: 5 Kudos [?]: 1 [0], given: 6 Re: M05-35 [#permalink] Show Tags 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, Kudos [?]: 1 [0], given: 6 Manager Joined: 12 Sep 2010 Posts: 241 Kudos [?]: 30 [1], given: 27 Concentration: Healthcare, General Management Re: M05-35 [#permalink] Show Tags 21 Aug 2015, 13:01 1 This post received KUDOS 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. Kudos [?]: 30 [1], given: 27 Intern Joined: 01 Aug 2015 Posts: 2 Kudos [?]: [0], given: 3 Re: M05-35 [#permalink] Show Tags 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?

Kudos [?]: [0], given: 3

Current Student
Joined: 12 Aug 2015
Posts: 300

Kudos [?]: 583 [0], given: 1474

Concentration: General Management, Operations
GMAT 1: 640 Q40 V37
GMAT 2: 650 Q43 V36
GMAT 3: 600 Q47 V27
GPA: 3.3
WE: Management Consulting (Consulting)

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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. _________________ KUDO me plenty Kudos [?]: 583 [0], given: 1474 Manager Joined: 08 Jul 2015 Posts: 58 Kudos [?]: 20 [0], given: 51 GPA: 3.8 WE: Project Management (Energy and Utilities) Re: M05-35 [#permalink] Show Tags 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 = $90. _________________ [4.33] In the end, what would you gain from everlasting remembrance? Absolutely nothing. So what is left worth living for? This alone: justice in thought, goodness in action, speech that cannot deceive, and a disposition glad of whatever comes, welcoming it as necessary, as familiar, as flowing from the same source and fountain as yourself. (Marcus Aurelius) Kudos [?]: 20 [0], given: 51 Intern Joined: 26 Dec 2016 Posts: 20 Kudos [?]: 3 [0], given: 13 Re: M05-35 [#permalink] Show Tags 10 Feb 2017, 04:23 shasadou wrote: I don't get why this problem is 95% hard rated. "Alone" eliminates right away D and E. Machine C is way too slow and expensive so choice C out. You can spend a minute and calculate to rule out whether B or A however at short reasoning B looks preferable. Why? Because it is faster when the time matters - attendat gets paid for the time spent and every additional minute could count. Although B is more costly in terms of$/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 ...

Kudos [?]: 3 [0], given: 13

Intern
Joined: 22 Jan 2017
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Kudos [?]: 9 [0], given: 5

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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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Math Expert
Joined: 02 Sep 2009
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Kudos [?]: 133014 [0], given: 12402

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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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Kudos [?]: 133014 [0], given: 12402

Re: M05-35   [#permalink] 01 Oct 2017, 04:53
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