KVPY Sample Paper KVPY Stream-SX Model Paper-8

  • question_answer
    \[\underset{n\to \infty }{\mathop{\lim }}\,\left[ \sum\limits_{r=1}^{n}{\frac{1}{2r}} \right],\] where [ ] denotes the greatest integer function, is equal to -

    A) 1                                 

    B) 0

    C) Non-existent                  

    D) None of these

    Correct Answer: B

    Solution :

    \[\underset{n\to \infty }{\mathop{\lim }}\,\left[ \frac{1}{2}+\frac{1}{{{2}^{2}}}+.....+\frac{1}{{{2}^{n}}} \right]\]
    \[\underset{n\to \infty }{\mathop{\lim }}\,\,\,\,\left[ \frac{1/2(1-1/{{2}^{n}})}{1-\frac{1}{2}} \right]\]
    \[\because \,\,\,\,n\to \infty \,\,1-1/{{2}^{n}}<1\]
    \[\therefore \,\,\,\,\underset{n\to \infty }{\mathop{\lim }}\,\left[ 1-\frac{1}{{{2}^{n}}} \right]=0\]


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