Correct Answer: Option A

Explanation

\(T_n = ar^{n - 1}\) (terms of a G.P)

\(T_3 = ar^2 = 9\) ... (i)

\(T_7 = ar^6 = \frac{1}{9}\) ... (ii)

Divide (i) by (ii);

\(\frac{ar^6}{ar^2} = \frac{\frac{1}{9}}{9}\)

\(r^4 = \frac{1}{81}\)

\(r^4 = (\frac{1}{3})^4\)

\(r = \frac{1}{3}\)

There is an explanation video available below.

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