document.write( "Question 1025775: a welder requires 24 hours to do a job. after the welder and apprentice work on the job for 12 hours, the welder quits. the apprentice finished the job in 9 hours. how long would it take the apprentice, working alone, to do the job? \n" ); document.write( "

Algebra.Com's Answer #641093 by ikleyn(52914) $\"\"$ $\"About$

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\n" ); document.write( "a welder requires 24 hours to do a job. After the welder and apprentice work on the job for 12 hours, the welder quits. The apprentice finished the job in 9 hours. How long would it take the apprentice, working alone, to do the job?
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document.write( "Let a = the rate-of-work (in units of ) of the apprentice.\r\n" );
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document.write( "We know that the welder's rate-of-work is  of the job-per-hour.\r\n" );
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document.write( "The balance equation is \r\n" );
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document.write( " = .\r\n" );
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document.write( "Simplify it:\r\n" );
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document.write( "9a =  - 12a,\r\n" );
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document.write( "21a = ,\r\n" );
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document.write( "a =  = .\r\n" );
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document.write( "Hence, it will take 42 hours for the apprentice to complete the job working alone.\r\n" );
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