pipes and work done
An inlet pipe can (by itself) fill an empty tank in two hours and an outlet pipe (by itself) can drain the same tank when full in five hours. If the tank is half full when the valves for both pipes are opened, how long will it take to fill the tank?
is the answer 1 hour and 40 minutes? i did it in my head so if someone would correct me if it's wrong id appreciate it.
In one hour, the inlet pipe fills 1/2 the tank.
Originally Posted by jarny
In one hour, the outlet pipe drains 1/5 of the tank.
So in one hour, the pipes fill 3/10 of the tank. Since the tank is half full to start with, you only need to fill 5/10 of it.
So it takes 5/3 hours to fill the tank. Which ends up being 1 hour and 40 minutes, so you're right :)