SOLUTION: Mary and Carol are doing a month project. Carol can do work twice as fast as Mary. If they work together they can finish the project in 4 hours. How long does it take to do the sam

Question 885981: Mary and Carol are doing a month project. Carol can do work twice as fast as Mary. If they work together they can finish the project in 4 hours. How long does it take to do the same project?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let Mary's rate of working =
in units of ( 1 project ) / ( time to do that project )
Carol's rate =
-----------------------
Add their rates of working to get their rate
working together

( the is ( 1 project / 4 hrs ) )
-----------------------------------

and

-------------------
Mary can do the project in 12 hrs
Carol can do the project in 6 hrs
----------------------------
check:

OK

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