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SSC Sample Paper SSC CGL - Sample Paper-15

  • question_answer
    The value of \[1-\frac{1}{20}+\frac{1}{{{(20)}^{2}}}-\frac{1}{{{(20)}^{3}}}+....\] correct to 5 places of decimals 4

    A) 1.05                             

    B) 0.95238

    C) 0.95239            

    D) 10.5

    Correct Answer: B

    Solution :

    Let \[x=1-\frac{1}{20}+\frac{1}{{{(20)}^{2}}}+\frac{1}{{{(20)}^{3}}}+...\] \[\Rightarrow \] \[x=1-\frac{1}{20}\left( 1-\frac{1}{20}+\frac{1}{{{(20)}^{2}}}+... \right)\] \[\Rightarrow \]   \[x=1-\frac{x}{20}\] \[\Rightarrow \]   \[x+\frac{x}{20}=1\] \[\Rightarrow \]   \[\frac{21x}{20}=1\]      \[\Rightarrow \]   \[x=\frac{20}{21}=0.95238\]


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