11th Class Mathematics Other Series Question Bank Critical Thinking

  • question_answer A G.P. consists of an even number of terms. If the sum of all the terms is 5 times the sum of the terms occupying odd places, then the common ratio will be equal to

    A) 2

    B) 3

    C) 4

    D) 5

    Correct Answer: B

    Solution :

    Let there be \[2n\] terms in the given G.P. with first term \[a\]and the common ratio\[r\]. Then, \[a\frac{({{r}^{2n}}-1)}{(r-1)}=5a\frac{({{r}^{2n}}-1)}{({{r}^{2}}-1)}\]\[\Rightarrow \]\[r+1=5\]\[\Rightarrow \]\[r=4\].


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