SOLUTION: a tank is 3/4 full . Fill Pipe A can fill the tank in 12 minutes . Drainpipe B can empty it in 8 minutes . if both pipes are open , how long will it take to empty the tank ?

Algebra ->  Rate-of-work-word-problems -> SOLUTION: a tank is 3/4 full . Fill Pipe A can fill the tank in 12 minutes . Drainpipe B can empty it in 8 minutes . if both pipes are open , how long will it take to empty the tank ?      Log On


   



Question 878361: a tank is 3/4 full . Fill Pipe A can fill the tank in 12 minutes . Drainpipe B can empty it in 8 minutes . if both pipes are open , how long will it take to empty the tank ?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
a tank is 3/4 full .
Fill Pipe A can fill the tank in 12 minutes .
Drainpipe B can empty it in 8 minutes .
if both pipes are open , how long will it take to empty the tank ?
:
let t = time to empty the tank with both pipes open
Let a full tank = 1, then 3/4 of a tank = .75
:
t%2F8 - t%2F12 = .75
multiply by 24, cancel the denominators
3t - 2t = 24(.75)
t = 18 minutes to empty the tank