Pipes and Cistern Basic Examples
In this class, We discuss Pipes and Cistern Basic Examples.
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Example 1:
A tap can fill a tank in 4 hours. At the same time, We can empty the tank with another tap in 9 hours.
If both the taps opened simultaneously, how much time will it take to fill the tank?
Solution:
In flow filled in 4 hours.
The part of the tank filled in one hour = 1/4
Outflow emptied in 9 hours.
The part of the tank emptied in one hour = 1/9.
Net part filled in one hour = 1/4 – 1/9.= 5/36.
Tank filled in 36/5 hours = 7.2 hours.
Important:
1/x part filled in one hour.
x hours needed to fill.
Example 2:
Two pipes can fill a tank in 10 and 12 hours, respectively. A third pipe can empty the full tank in 20 hours.
If all the pipes operate simultaneously, how much time will it take to fill the tank?
Solution:
Pipe A takes 10 hours to fill the tank
Pipe B takes 12 hours to fill the tank.
(A + B) one hour capacity = (1/10 + 1/12)
Pipe C can empty the tank in 20 hours.
C’s one-hour empty capacity = 1/20
All pipes work simultaneously.
Net part filled in one hour = ((1/10 + 1/12) – 1/20) = 2/15
The tank will be full in 15/2 hours.
= 7.5 hours.