If the sum of n terms of the series 1, 3, 9, 27, ..... is 121. Find the value of n.

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Solution

The correct option is D
5

The n^th term of the sequence is given by $3^{(n - 1)}$ and it is in G.P.

$(3^{n} - 1) / (3 - 1) = 121 3^{n} = 243$

The value of n is 5

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