SOLUTION: One cement mason can lay a cement foundation in 8 hours, while it takes a second 12 hours to do the same task. After working alone for 4 hours, the fist mason quits. How long will

Algebra ->  Equations -> SOLUTION: One cement mason can lay a cement foundation in 8 hours, while it takes a second 12 hours to do the same task. After working alone for 4 hours, the fist mason quits. How long will       Log On


   

Question 889689: One cement mason can lay a cement foundation in 8 hours, while it takes a second 12 hours to do the same task. After working alone for 4 hours, the fist mason quits. How long will it take the second mason to complete the task?
Thank you very much!
Found 2 solutions by josgarithmetic, JulietG:
Answer by josgarithmetic(39615) About Me  (Show Source):
You can put this solution on YOUR website!
Uniform Rates of each mason:
1%2F8 and 1%2F12 in unit of foundation%2Fhour.

Basic uniform rate idea is RT=J rate time job.

Let h = time in hours for the second mason to finish after the first mason stops. The two masons do not work simultaneously.

highlight_green%28%281%2F8%294%2B%281%2F12%29h=1%29.
Solve for h.

Answer by JulietG(1812) About Me  (Show Source):
You can put this solution on YOUR website!
The first mason has completed 4%2F8 of the task. It's half done. The second mason has to complete the second half -- it takes him 12 hours for the full task, so half of that for half a task. 12/2 = 6 more hours.