SOLUTION: Working alone, it takes Emily seven hours to dig a 10ft by 10ft hole. Norachai can dig the same hole in six hours. How long would it take them if they worked together?

Question 284736: Working alone, it takes Emily seven hours to dig a 10ft by 10ft hole. Norachai can dig the same hole in six hours. How long would it take them if they worked together?
Found 2 solutions by checkley77, Alan3354:
Answer by checkley77(12844) (Show Source): You can put this solution on YOUR website!
1/7+1/6=1/X
(6+7)/6*7=1/X
13/42=1/X
13X=42
X=42/13
X=3.23 HOURS WHEN THEY WORK TOGETHER.
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
wouldn't they get in each other's way?
Ignoring that, use product/sum
6*7/(6+7) = 42/13 hours

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