SOLUTION: A new copying machine can do a certain job in 1 hour less than an older copier. Together they can do this job in 72 minutes. How long would it take the older copier by itself to do
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Question 269748: A new copying machine can do a certain job in 1 hour less than an older copier. Together they can do this job in 72 minutes. How long would it take the older copier by itself to do the job
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
A new copying machine can do a certain job in 1 hour less than an older copier. Together they can do this job in 72 minutes. How long would it take the older copier by itself to do the job>
:
Change 72 min; 72/60 = 1.2 hrs
:
Let x = time for the older copier to do the job
then
(x-1) = time required by the new copier
:
Let the completed job = 1
:
Each copier will do a fraction of the job, the two factions add up to 1
+ = 1
Multiply equation by x(x-1); results:
1.2(x-1) + 1.2x = x(x-1)
:
1.2x - 1.2 + 1.2x = x^2 - x
:
2.4x - 1.2 = x^2 - x
Arrange as a quadratic equation
x^2 - x - 2.4x + 1.2 = 0
x^2 - 3.4x + 1.2 = 0
Factors to
(x-3)(x-.4) = 0
Two solutions
x = 3 hrs is the reasonable answer for the older machine
:
:
check solution
1.2/3 + 1.2/2 =
.4 + .6 = 1
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