Sum of a G.P. series is represented by the formula, , when r>1. ‘S_n’ represents the sum of the G.P. series upto n^th terms, ‘a’ represents the first term, ‘r’ represents the common ratio and ‘n’ represents the number of terms.

Here,

a = 1

r = (ratio between the n term and n-1 term) 3 ÷ 1 = 3

n = 7 terms

∴

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