November 2012


I am afraid this is all about quadratic equations.

Well, let us consider the number of crows to be "x". The square root of half of them took flight when I approached them. So, the number of crows that took flight is square-root (x/2).

Two crows, at present, have hopped to the side. The rest of the birds, comprising eight-ninths of the flock, are feasting.

Thus, the two birds which hopped to the side and square-root (x/2) number of birds constitute one-ninth of the flock.

Therefore, 2+square-root(x/2) = 1/9*x, that is, 2+square-root(x/2)=x/9.

Therefore, square-root(x/2) = (x/9)-2.

Squaring both sides we get, x/2 = x2/81 - 4x/9 + 4.

Simplifying we get x/2 = (x2 - 36x + 324)/ 81.

That is, 81x = 2x2 - 72x + 648.

That is, 2x2 - 153x + 648 = 0.

Now this is a quadratic equation of the form ax2 + bx + c = 0 whose solutions are: (-b +/- square-root (b2 - 4ac))/2a. So, solving we get x is either 72 or 4.5. But whoever heard of 4.5 birds. The number of crows was, therefore, 72.

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 -

DISCLAIMER: The contents of this website are for informational purposes only. Although due care is taken, the correctness and accuracy cannot be guaranteed. The science and medical research articles are for informational purposes only, aimed at kindling an interest in science. They are not intended to provide any kind of advice.