Pipes and pipe dreams
While in school, math questions of the kind "If a small pipe fills up a cistern in 40 minutes and a big pipe fills up the cistern in 20 minutes, how long will it take for both the pipes together to fill up the cistern?" always had the effect of leaving me completely washed out.
Once I passed out of school, I thought pipes had passed out of my life also. But, no! That was only a pipe dream. The pipes made their appearance in aptitude questions later in life.
Having crossed that stage of life also, I was sure now pipes will not trouble me anymore. That again was wishful thinking.
Before leaving for work every day, I have to fill up a water storage tank. The narrow pipe I employed for the purpose took a long time to fill the tank. I obtained a wider pipe, and things have brightened up for me.
All these talk about pipes, has once again brought to mind the questions which tormented me in school. My question is: The wide pipe fills up the tank three times as fast as the narrow one. Both the pipes together fill up the tank in 40 minutes. How long does the narrow pipe, then, take to fill up the tank all on its own?