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GRE Prep Club Team Member
Joined: 20 Feb 2017
Posts: 2508
Given Kudos: 1053
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One printing press can print a daily newspaper in 12 hours,
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23 Mar 2020, 00:04
23 Mar 2020, 00:04
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Question Stats:
92% (00:45) correct
7% (00:00) wrong based on 13 sessions
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One printing press can print a daily newspaper in 12 hours, while another press can print it in 18 hours. How long will the job take if both presses work simultaneously?
(A) 7 hours, 12 minutes
(B) 9 hours, 30 minutes
(C) 10 hours, 45 minutes
(D) 15 hours
(E) 30 hours
(A) 7 hours, 12 minutes
(B) 9 hours, 30 minutes
(C) 10 hours, 45 minutes
(D) 15 hours
(E) 30 hours
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One printing press can print a daily newspaper in 12 hours,
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12 Feb 2021, 11:55
12 Feb 2021, 11:55
1
If A can do a piece of job in X time, while B can do it in Y time, then working together, they both can finish the job in;
T =\(\frac{XY}{(X + Y)}\) time
T = \(\frac{(12)(18)}{(12 + 18)}\) = \(\frac{36}{5}\)
T is approximately 7+ hours
Hence, option A
T =\(\frac{XY}{(X + Y)}\) time
T = \(\frac{(12)(18)}{(12 + 18)}\) = \(\frac{36}{5}\)
T is approximately 7+ hours
Hence, option A
One printing press can print a daily newspaper in 12 hours,
[#permalink]
13 Feb 2021, 09:34
13 Feb 2021, 09:34
1
Hi,
This can be solved by finding the LCM of the two time taken by the two machines to complete the work.
The LCM of 12 & 18= 36
------------Time taken------ Units of work done per hour
Machine 1 --12 hrs-------36/12=3 units per hour
Machine 2 --18 hrs-------36/18= 2 units per hour
Now, as we know the machines do 3 and 2 units per hour, together they both will do 3+2 units per hour
Thus, the machines will together require 36/5=7 hours and 12 mins
IMO A
Hope this helps!
This can be solved by finding the LCM of the two time taken by the two machines to complete the work.
The LCM of 12 & 18= 36
------------Time taken------ Units of work done per hour
Machine 1 --12 hrs-------36/12=3 units per hour
Machine 2 --18 hrs-------36/18= 2 units per hour
Now, as we know the machines do 3 and 2 units per hour, together they both will do 3+2 units per hour
Thus, the machines will together require 36/5=7 hours and 12 mins
IMO A
Hope this helps!
