I.S.I. and C.M.I. Entrance

ISI Entrance Paper BMath 2011 – Subjective

ISI Entrance Paper BMath 2011 – from Indian Statistical Institute’s Entrance

Also see: ISI and CMI Entrance Course at Cheenta

  1. Given \mathbf{ a,x\in\mathbb{R}} and \mathbf{x\geq 0,a\geq 0} . Also \mathbf{sin(\sqrt{x+a})=sin(\sqrt{x})} . What can you say about a? Justify your answer.
  2. Given two cubes R and S with integer sides of lengths r and s units respectively . If the difference between volumes of the two cubes is equal to the difference in their surface areas , then prove that r=s.
  3. For \mathbf{n\in\mathbb{N}} prove that \mathbf{\frac{1}{2}\cdot\frac{3}{4}\cdot\frac{5}{6}\cdots\frac{2n-1}{2n}\leq\frac{1}{\sqrt{2n+1}}}
  4. Let \mathbf{t_1 < t_2 < t_3 < \cdots < t_{99}} be real numbers. Consider a function \mathbf{f: \mathbb{R} to \mathbb{R}} given by \mathbf{f(x)=|x-t_1|+|x-t_2|+...+|x-t_{99}|} . Show that f(x) will attain minimum value at \mathbf{x=t_{50}}
  5. Consider a sequence denoted by F_n of non-square numbers . \mathbf{F_1=2,F_2=3,F_3=5} and so on . Now , if \mathbf{m^2\leq F_n<(m+1)^2} . Then prove that m is the integer closest to \mathbf{\sqrt{n}}
  6. Let \mathbf{f(x)=e^{-x} for all x\geq 0} and let g be a function defined as for every integer \mathbf{k \ge 0}, a straight line joining (k,f(k)) and (k+1,f(k+1)) . Find the area between the graphs of f and g.
  7. If \mathbf{a_1, a_2, \cdots, a_7} are not necessarily distinct real numbers such that \mathbf{1 < a_i < 13} for all i, then show that we can choose three of them such that they are the lengths of the sides of a triangle.
  8. In a triangle ABC , we have a point O on BC . Now show that there exists a line l such that l||AO and l divides the triangle ABC into two halves of equal area.

By Dr. Ashani Dasgupta

Ph.D. in Mathematics, University of Wisconsin, Milwaukee, United States.

Research Interest: Geometric Group Theory, Relatively Hyperbolic Groups.

Founder, Cheenta

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