SOLUTION: A can do a certain job, working alone, in 3.15 hours. Working with B, A can do the same job in 2.09 hours. How long will it take B, working alone, to do the job?

Question 754983: A can do a certain job, working alone, in 3.15 hours. Working with B, A can do the same job in 2.09 hours. How long will it take B, working alone, to do the job?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
A can do a certain job, working alone, in 3.15 hours.
Working with B, A can do the same job in 2.09 hours.
How long will it take B, working alone, to do the job?
:
Let b = time required by B working alone
Let the completed job = 1
:
Each will do a fraction of the job, the two fractions add up to 1
+ = 1
mult by 3.15b to clear the denominators, results:
2.09b + 3.15(2.09) = 3.15b
6.5835 = 3.15b - 2.09b
6.5835 = 1.06b
b = 6.5835/1.06
b = 6.21 hrs, B working alone
:
:
Check on a calc
+ =
.6635 + .3365 = 1.00; confirms our solution of b = 6.21 hrs
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