SOLUTION: Two painters were working on a house. Painter A can complete the given job in 8 hours but painter B takes 10 hourse. They worked together for the first four hours, but painter A le

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Two painters were working on a house. Painter A can complete the given job in 8 hours but painter B takes 10 hourse. They worked together for the first four hours, but painter A le      Log On


   

Question 990815: Two painters were working on a house. Painter A can complete the given job in 8 hours but painter B takes 10 hourse. They worked together for the first four hours, but painter A left and told painter B to finish thejob. How long would it take for painter B to finish the job?
Found 2 solutions by Philipsokleva, Edwin McCravy:
Answer by Philipsokleva(4) About Me  (Show Source):
You can put this solution on YOUR website!
In 8hours!!!

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
The other tutor's answer is incorrect.

Two painters were working on a house. Painter A can complete the given job in 8
hours
Painter A's rate is 1 job per 8 hours or 1/8 job per hour

but painter B takes 10 hours.
Painter B's rate is 1 job per 10 hours or 1/10 job per hour

They worked together for the first four hours, 
Their combined rate is 1/8 + 1/10 = 5/40 + 4/40 = 9/40 job per hour.

In those 4 hours at that rate they did 4(9/40) or 9/10 of the job.

So 1/10 of the job remained to be done.

but painter A left and told painter B to finish the job.
How long would it take for painter B to finish the job? 
Let the answer be x hours.  Then rate times time = the remaining 1/10

B's rate is 1/10 jobs per hour, so the equation is rate times time = 1/10.

              (1/10)(x) = 1/10
                      x = 1 hour.

Edwin