SOLUTION: Pipe A can fill a tank in 25 minutes. Pipe B can fill the same tank in 20 minutes. To fill the empty tank, pipe A was opened alone for 3 minutes, and, after that, pipe B was also o

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Pipe A can fill a tank in 25 minutes. Pipe B can fill the same tank in 20 minutes. To fill the empty tank, pipe A was opened alone for 3 minutes, and, after that, pipe B was also o      Log On


   

Question 925866: Pipe A can fill a tank in 25 minutes. Pipe B can fill the same tank in 20 minutes. To fill the empty tank, pipe A was opened alone for 3 minutes, and, after that, pipe B was also opened. How much time will it take for both pipes, A and B to finish filling the tank?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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Pipe A can fill a tank in 25 minutes.
Pipe B can fill the same tank in 20 minutes.
To fill the empty tank, pipe A was opened alone for 3 minutes, and, after that, pipe B was also opened.
How much time will it take for both pipes, A and B to finish filling the tank?
:
let t = for A & B to finish filling the tank
let the completed job = 1 (a full tank)
:
A shared work equation
%28%28t%2B3%29%29%2F25 + t%2F20 - 1
multiply equation by 100, cancel the denominators
4(t+3) + 5t = 100
4t + 12 + 5t = 100
4t + 5t = 100 - 12
9t = 88
t = 9.78 minutes for A & B to finish filling the tank