September 2011


I had four parrots and three cages.

If you put one parrot in each cage, you have an extra bird without a cage. However, if you put two parrots in each cage, then you have an extra cage.

Let there be x birds and y cages, then we get the following equations:

y=x-1 (because the number of cages is one less than the number of birds)

and 2(y-1)=x (because two birds in one cage will lead to one extra cage, that is y-1 cages will be required to house x birds).

Solving, we get x=4 and y=3.

Some useful links for
your career:

  • Union Public Service Commission -
  • IIT-Kharagpur -
  • Indian Statistical Institute -
  • Indian Institute of Technology Madras -
  • Indian Institute of Management, Ahmedabad -
  • Indian Institute of Mass Commission -
  • IIT Bombay -
  • Indian School of Mines, Dhanbad -
  • Birla Institute of Technology, Ranchi -
  • Central Institute of Fisheries Nautical and Engineering Training -
  • Indian Institute of Information Technology, Allahabad (Deemed University) -
  • Central Marine Fisheries Research Institute, Kochi -
  • Tata Institute of Social Sciences, Mumbai -

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