SOLUTION: a tank can be filled by one pipe in 30 minutes and emptied by another in 50 minutes. if both pipes are open how long will it take to fill the tank?

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Question 781995: a tank can be filled by one pipe in 30 minutes and emptied by another in 50 minutes. if both pipes are open how long will it take to fill the tank?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The rate of filling is: ( 1 tank ) / ( 30 min )
The rate of emptying is: ( minus 1 tank ) / ( 50 min )
Let +t+ = time in minutes to fill the tank
+1%2F30+-+1%2F50+=+1%2Ft+
Multiply both sides by +150t+
+5t+-+3t+=+150+
+2t+=+150+
+t+=+75+
It will take 75 min or 1 hr and 15 min to fill the tank