A math problem:
It takes sis hours for two printing presses to print a newspaper. How long would it take seven presses to do the job?
2007-05-30 18:44:18 · 6 answers · asked by The One 1 in Science & Mathematics ➔ Mathematics
Okay first assume all printing presses are of the same ability and speed. You know 2 presses take six hours. So one press will take double the time right?
2 presses = 6 hours
1 press = 6 hours * 2 = 12 hours.
Now one press takes 12 hours to do the job.
If there are 7 presses, think of it like each press has to do 1/7th of the job it had to do if it was doing the work alone. So the total job would take 12/7 hours.
2007-05-30 18:51:33 · answer #1 · answered by Nikhil M 3 · 0⤊ 0⤋
its more of a ratio to me...
hours:presses
6:2
_:7
2 / 6 is equal to three so 1 press can take 3 hours so 3 x 7=21.
7 presses can make 3 newspapers in 18 hours with an extra time of 2 hours
90% sure
2007-05-31 03:02:54 · answer #2 · answered by karlo de guzman 3 · 0⤊ 0⤋
Six hours for two presses means that one press could do it in 12 hours, or "12 press hours". So, if you had seven presses, you divided 12 hours of total work by seven presses, and that's your answer.
2007-05-31 01:52:31 · answer #3 · answered by Katherine W 7 · 0⤊ 0⤋
amount of work = 2 X 6 press-hours
time for seven presses to do the work = work / no of presses
(similarly no of presses to do the work = work / time)
= 2 X 6 / 7 = 12/7 hrs
2007-05-31 01:53:25 · answer #4 · answered by Karoly 2 · 0⤊ 0⤋
You have to add the rates.
2 presses operate at a rate of1/6 jobs per hour
7 presses operate at a rate of 7/2 * 1/6 jobs per hour
= 7/12 jobs per hour
So they take 12/7 hours to do one job
2007-05-31 02:00:01 · answer #5 · answered by Dr D 7 · 0⤊ 0⤋
if two printing presses takes six hours
then seven take x hours.
now cross multiply the integrers
so x=2\7*6=1.71 hours .
this is a inverse proportion question,
ask your teacher to help you with this,
sorry i couldn't explain much.
2007-05-31 01:52:07 · answer #6 · answered by Dr. Eddie 6 · 0⤊ 0⤋