For a sequence $ < {a_n} > ,\;{a_1} = 2$ and $\frac{{{a_{n + 1}}}}{{{a_n}}} = \frac{1}{3}$. Then $\sum\limits_{r = 1}^{20} {{a_r}} $ is
For a sequence $ < {a_n} > ,\;{a_1} = 2$ and $\frac{{{a_{n + 1}}}}{{{a_n}}} = \frac{1}{3}$. Then $\sum\limits_{r = 1}^{20} {{a_r}} $ is
- A
$\frac{{20}}{2}[4 + 19 \times 3]$
- B
$3\left( {1 - \frac{1}{{{3^{20}}}}} \right)$
- C
$2(1 - {3^{20}})$
- D
None of these
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