CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2001

  • question_answer
    How many terms of the geometric series 1+ 4 + 16 + 64 + ... will make the sum 5461?

    A)  7                            

    B)  8

    C)  27                         

    D)         28

    E)  31

    Correct Answer: A

    Solution :

                    Let number of terms be n. \[\therefore \]  \[5461=\frac{1({{4}^{n}}-1)}{4-1}\] \[\Rightarrow \]               \[5461\times 3={{4}^{n}}-1\] \[\Rightarrow \]               \[{{4}^{n}}=16384\] \[\Rightarrow \]               \[{{4}^{n}}={{4}^{7}}\] \[\Rightarrow \]               \[n=7\] \[\therefore \]7 terms of GP make the sum 5461.


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