Question 1186169: An office needs 20 copies of a 420-page report. One photocopier can copy 1800 pages per hour. Another copier is faster and can copy 2400 pages per hour. To find the time it would take the two copiers together to complete the project, you can use this verbal model. Assign labels to the model to form an equation. "the rate of the first machine" 'times' "the time to complete" 'plus' "the rate of the second machine" 'times' "the time to complete" 'equals' "total pages"
Found 3 solutions by ikleyn, josgarithmetic, greenestamps:
Answer by ikleyn(52777)   (Show Source):
You can put this solution on YOUR website! .
An office needs 20 copies of a 420-page report. One photocopier can copy 1800 pages per hour.
Another copier is faster and can copy 2400 pages per hour. To find the time it would take the two copiers
together to complete the project, you can use this verbal model. Assign labels to the model to form an equation.
"the rate of the first machine" 'times' "the time to complete" 'plus' "the rate of the second machine" 'times'
"the time to complete" 'equals' "total pages"
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Do you consider tutors as parrots ?
Does your teacher/professor consider you, the students, as parrots ?
Who gave you this assignment ?
Or, in other words, where did you find/take/recover it ?
You really scared me . . .
I really think if it is just time to call for urgent medical help for me.
. . . What it was ? . . .
//////////////////////////////////////////////////
To the managers of this project (!)
Warning (!) Warning (!) Warning (!)
I ask you urgently, please, to remove the person, who submitted this post,
from his position in this project for posting nonsensical frightening messages (!)
. . . . . . . . . . . . . . . .
At the same time, it also would be good to remove so called "tutor" @josgarithmetic from the forum
for his total inability to solve Math problems correctly . . . and for his total inability to teach Math . . .
In his post, related to this problem, he was not able to multiply correctly two numbers, giving total 840 pages (incorrectly)
instead of correct value of 20*420 = 8400 pages.
I just do not say about full solution of the problem.
Answer by josgarithmetic(39617)  (Show Source):
You can put this solution on YOUR website! 
RATE, pages per hour
Onecopier 1800
Anothercopier 2400
Together 4200
Simple rate-of-work problem, and the question only requires common skills in language writing mechanics.
Answer by greenestamps(13198)  (Show Source):
You can put this solution on YOUR website!
Using the model suggested in your post....
Let t = # of hours to complete the job
(pages per hour of the first machine) * (# of hours to complete) + (pages per hour of the second machine) * (# of hours to complete) = (total pages)
(1800)(t)+(2400)(t)=20(420)
1800t+2400t=8400
4200t=8400
t=8400/4200=2
ANSWER: 2 hours
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