Value of \( S=\sum_{k=1}^{\infty} \sum_{r=0}^{k} \frac{1}{3^{k}}\left({ }^{k} C_{r}\right) \) is...
Value of \( S=\sum_{k=1}^{\infty} \sum_{r=0}^{k} \frac{1}{3^{k}}\left({ }^{k} C_{r}\right) \) is
(a) 2
(b) \( \frac{2}{3} \)
(c) \( \frac{1}{3} \)
(d) none of these
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