SOLUTION: A wind generator can charge 20 storage batteries in 24 h . After the generator has been charging for 6.0 h , another generator, which can charge the batteries in 36 h , is also c

Question 1055498: A wind generator can charge 20 storage batteries in 24 h . After the generator has been charging for 6.0 h , another generator, which can charge the batteries in 36 h , is also connected to the batteries. How many additional hours are needed to charge the 20 batteries?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
The rate of charging for the wind
generator is [ 1 pack ] / [ 24 hrs ]
( I can call the 20 storage batteries 1 pack
because the problem is only about the 20
batteries, never more & never less. )
---------------------------------------
The fraction of charging after 6 hrs is:

There is of the charging job
left to do
-------------------------------------------
Now you have 2 generators charging the pack.
Add their rates of charging.
Let = time to do the of the charging job

Multiply both sides by

-------------------------------
10.8 additional hours are needed
to charge the 20 batteries
-------------------------------
check:

error due to rounding off, I think
OK

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