SOLUTION: Two printing presses are available to print the daily college newspaper. If only one press is used, it takes the older press twice as long to print an edition as it takes the newer

Question 1117108: Two printing presses are available to print the daily college newspaper. If only one press is used, it takes the older press twice as long to print an edition as it takes the newer press. If the two presses together can print an edition in 3 hours, how long would it take for each press alone to print an edition?
Answer by ikleyn(52781) (Show Source): You can put this solution on YOUR website!
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1. Mental solution

It is the same as to have THREE identical printers, where 2 of them "replace" and "play the role" of one newer printer.


So, if the three printers do the entire job in 3 hours, it means that each of the three, working alone, will do the job in 9 hours.


Answer.  9 hours for old printer and  = 4.5 hours for newer printer each working alone.

Solved.

2. Algebra solution

Let x be the rate of work of the slower printer, measured in "job-per-hour".


Then the rate of work of the faster printer is 2x "jobs-per-hour", according to the condition.


Also, according to the condition,


x + 2x =   of the job per hour,    or


3x = .


It implies  x = ,   which means that the slower printer makes    of the job per hour.


In turn, it means that the slower printer will make the entire job in 9 hours, working alone.


And you get the same answer.

Solved.

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