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第17页

信息发布者：

$=1− (\frac {1}{2}+\frac {1}{4}+\frac {1}{8}+\frac {1}{16}+\frac {1}{32}+\frac {1}{64})$

$=1−(1−\frac {1}{64})$

$=1−\frac {63}{64}$

$=\frac {1}{64}$

$=\frac {1}{2}+(\frac {1}{3}+\frac {2}{3})+(\frac {1}{4}+\frac {2}{4}+\frac {3}{4})+(\frac {1}{5}+\frac {2}{5}+\frac {3}{5}+\frac {4}{5})$

$+.….+(\frac {1}{12}+\frac {2}{12}+.….+\frac {11}{12})$

$=\frac {1}{2}+\frac {2}{2}+\frac {3}{2}+\frac {4}{2}+.….+\frac {11}{2}$

$=\frac {1}{2}+1+\frac {3}{2}+2+.….+\frac {11}{2}$

$=15+\frac {36}{2}$

$=15+18$

$=33$

$\frac{13}{60}$