SOLUTION: A tank can be filled by two pipes separately in 10 and 15 minutes respectively. When a third pipe is used simultaneously with the first two pipes, the tank can be filled in 4 minu

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: A tank can be filled by two pipes separately in 10 and 15 minutes respectively. When a third pipe is used simultaneously with the first two pipes, the tank can be filled in 4 minu      Log On


   

Question 667145: A tank can be filled by two pipes separately in 10 and 15 minutes respectively.
When a third pipe is used simultaneously with the first two pipes, the tank can be filled in 4 minutes. How long would it take the third pipe alone to fill the tank?
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
A tank can be filled by two pipes separately in 10 and 15 minutes respectively.
When a third pipe is used simultaneously with the first two pipes, the tank can be filled in 4 minutes. How long would it take the third pipe alone to fill the tank
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let x= How long would it take the third pipe alone to fill the tank
1/10=work rate of 1st pipe
1/15=work rate of 2nd pipe
1/x=work rate of 3rd pipe
1/4=work rate of 3 pipes working together
..
sum of individual work rates=work rate working together
1/10+1/15+1/x=1/4
1/x=1/4-1/10-1/15
=15/60-6/60-4/60
=5/60
1/x=1/12
x=12
How long would it take the third pipe alone to fill the tank=12 min