guerrero wrote: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
OAB
Machine A:
Time = pages/rate = 1200/12 = 100 minutes.
Since the time is between 1 and 2 hours, the worker is paid for 2 hours.
Worker cost = (hourly wage)(number of hours) = r*t = 30*2 = $60.
Page cost = (cents per page)(number of pages) = 8*1200 = 9600 cents = $96.
Total cost = 60+96 = $156.
Machine B:
Time = pages/rate = 1200/7 ≈ 170 minutes.
Since the time is between 2 and 3 hours, the worker is paid for 3 hours.
Worker cost = (hourly wage)(number of hours) = r*t = 30*3 = $90.
Page cost = (cents per page)(number of pages) = 5*1200 = 6000 cents = $60.
Total cost = 90+60 = $150.
Since B is a better option than A, eliminate A.
Machine C:
Time = pages/rate = 1200/19 ≈ 60+ minutes.
Since the time is between 1 and 2 hours, the worker is paid for 2 hours.
Since A's time is also 2 hours, and A's page cost is LESS than C's, A is a better option than C.
Thus, B is better than A, and A is better than C, B is better than C.
Eliminate C.
Machines A and B together:
Since their combined rate = 7+12 = 19 pages per minute, the time will be the same as C's time (2 hours).
Cost for 2 attendants working for 2 hours each = (number of workers)(hourly rate)(number of hours) = 2*30*2 = $120.
Since B's page cost for the entire job = $60, and A's page cost is GREATER than B's, the total cost for A and B together must be MORE than 120+60 = $180.
Thus, B alone is a better option.
Eliminate D.
Machines A and C together:
Since their combined rate = 7+19 = 26 pages per minute, the time for A and C together = pages/(combined rate) = 1200/26 = less than 60 minutes.
Since the time is less than 1 hour, the 2 workers are paid for 1 hour each.
Cost for 2 attendants working for 1 hour each = (number of workers)(hourly rate)(number of hours) = 2*30*1 = $60.
Since A's page cost for the entire job = $96, and C's page cost is GREATER than A's, the total cost for A and C together must be MORE than 60+96 = $156.
Thus, B alone is a better option.
Eliminate E.
The correct answer is
B.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at
[email protected].
Student Review #1
Student Review #2
Student Review #3
