SOLUTION: an older machine can do a job in 104 minuets, it takes only 40 minuets when a newer machine works simultaneously. how long would it take the newer machine to do the job working alo

Question 535304: an older machine can do a job in 104 minuets, it takes only 40 minuets when a newer machine works simultaneously. how long would it take the newer machine to do the job working alone?
Found 2 solutions by nerdybill, oberobic:
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
an older machine can do a job in 104 minuets, it takes only 40 minuets when a newer machine works simultaneously. how long would it take the newer machine to do the job working alone?
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Let x = time (minutes) it takes for newer machine alone
then
40(1/104 + 1/x) = 1
multiplyb both sides 104x:
40(x + 104) = 104x
40x + 4160 = 104x
4160 = 64x
65 minutes = x

Answer by oberobic(2304) (Show Source): You can put this solution on YOUR website!
Shared work problems like this one can be solved by considering the faction of the work that can be done in some period of time by each resource and then summing them to a total of 1.
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The older machine takes 104 minutes to do the work, so we can say it does 1/104 of the job per minute. Working with the new machine, the job can be done in 40 minutes.
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So, the new machine can do the job in 65 minutes.
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To check the work, compute how much work each machine will do in 40 minutes.
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Correct.
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Done.
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