document.write( "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 \n" ); document.write( "

Algebra.Com's Answer #197664 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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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>
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\n" ); document.write( "Change 72 min; 72/60 = 1.2 hrs
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\n" ); document.write( "Let x = time for the older copier to do the job
\n" ); document.write( "then
\n" ); document.write( "(x-1) = time required by the new copier
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\n" ); document.write( "Let the completed job = 1
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\n" ); document.write( "Each copier will do a fraction of the job, the two factions add up to 1
\n" ); document.write( " $\"1.2%2Fx\"$ + $\"1.2%2F%28%28x-1%29%29\"$ = 1
\n" ); document.write( "Multiply equation by x(x-1); results:
\n" ); document.write( "1.2(x-1) + 1.2x = x(x-1)
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\n" ); document.write( "1.2x - 1.2 + 1.2x = x^2 - x
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\n" ); document.write( "2.4x - 1.2 = x^2 - x
\n" ); document.write( "Arrange as a quadratic equation
\n" ); document.write( "x^2 - x - 2.4x + 1.2 = 0
\n" ); document.write( "x^2 - 3.4x + 1.2 = 0
\n" ); document.write( "Factors to
\n" ); document.write( "(x-3)(x-.4) = 0
\n" ); document.write( "Two solutions
\n" ); document.write( "x = 3 hrs is the reasonable answer for the older machine
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\n" ); document.write( "check solution
\n" ); document.write( "1.2/3 + 1.2/2 =
\n" ); document.write( ".4 + .6 = 1
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