SOLUTION: out of four pipes when 1,2,3 pipes are opened tank filled in 12 minutes; when 2,3,4 pipes opened time taken is 15 minutes;when 1 and 2 are opened it taken 20 minutes. How much time

Question 550035: out of four pipes when 1,2,3 pipes are opened tank filled in 12 minutes; when 2,3,4 pipes opened time taken is 15 minutes;when 1 and 2 are opened it taken 20 minutes. How much time will take when all the four pipes are opened?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
The pipes are assumed to fill tank at different rates
Let = rate for pipe 1
Let = rate for pipe 2
Let = rate for pipe 3
Let = rate for pipe 4
-----------------------
given:
(1)
(2)
(3)
------------------
Substitute (3) into (1)
(1)
(1)
(1)
(1)
-----------------
This is 4 unknowns and only 3 equations.
Is some data missing?
I don't think this can be solved
RELATED QUESTIONS
out of four pipes when 1,2,3 pipes are opened tank filled in 12 minutes; when 2,3,4 pipes (answered by ankor@dixie-net.com)

When 2 pipes are open, a tank is filled in 12 minutes. On one occasion, the first pipe... (answered by lwsshak3)

Two pipes can fill a tank in 18 minutes & 27 minutes individually.A third pipe can empty... (answered by josgarithmetic,Edwin McCravy,AnlytcPhil)

Filling a tank. A water tank has an inlet pipe and a drain pipe. A full tank can be... (answered by jim_thompson5910)

Filling a tank. A water tank has an inlet pipe and a drain pipe. A full tank can be... (answered by scott8148)

Filling a tank. A water tank has an inlet pipe and a drain pipe. A full tank can be... (answered by stanbon)

Filling a tank. A water tank has an inlet pipe and a drain pipe. A full tank can be... (answered by josmiceli)

Filling a tank. A water tank has an inlet pipe and a drain pipe. A full tank can be... (answered by solver91311)

Filling a tank. A water tank has an inlet pipe and a drain pipe. A full tank can be... (answered by solver91311,stanbon)