SOLUTION: A larger pipe can empty a pool in 6 hrs and a smaller pipe can empty the same pool in 9 hrs. How long will it take both pipes to empty the pool?

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Question 387668: A larger pipe can empty a pool in 6 hrs and a smaller pipe can empty the same pool in 9 hrs. How long will it take both pipes to empty the pool?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add their rates of emptying to get rate for both
In words:
{1 pool)/(6 hours) + (1 pool)/(9 hours) = (1 pool)/(x hours)
1%2F6+%2B+1%2F9+=+1%2Fx
Multiply both sides by 18x
3x+%2B+2x+=+18
5x+=+18
x+=+3.6
It will take 3.6 hrs or 3 hours and 36 minutes