The number of terms, 'n' is 8
Let's determine the common ratio;
common ratio, r = 3/1 = 3
The formula for sum of geometric series with 'r' greater than 1 is given as; Sn = a( r^n - 1) / (r - 1)
n is unknown
Sn = 3280
Substitute the value
3280 = 1 ( 3^n - 1) / 3- 1
3280 = 3^n -1 /2
Cross multiply
3280 × 2 = 3^n - 1
6560 + 1 = 3^n
6561 = 3^n
This could be represented as;
3^8 = 3^n
like coefficient cancels out
n = 8
Thus, the number of terms, 'n' is 8
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