Pipes & Cisterns Aptitude Questions And Solutions

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  Ankita Katdare

  I will start with some basic formulae that one should know to solve these kind of problems.
  
  What is inlet?
  A pipe connected with a tank or cistern that fills it, is called as inlet.
  
  What is outlet?
  A pipe connected with a tank or cistern that empties it, is called as outlet.
  
  1. If a pipe can fill a tank in 'n' hours, then the part of tank filled in one hour is 1/n.
  
  2. If a pipe can empty a tank in 'm' hours, then the part emptied in one hour is 1/m.
  
  3. If a pipe fills a tank in 'n' hours and another pipe empties the tank in 'm' hours, such that m>n, then on opening both the pipes, the net part filled in one hour is 1/n - 1/m.
  
  4. If a pipe fills a tank in 'n' hours and another pipe empties the tank in 'm' hours, such that n>m, then on opening both the pipes, the net part emptied in one hour is 1/m - 1/n.