Answer
$0.965$
Work Step by Step
$P(X\geq3)=1-P(X\lt3)=1-(P(X=0)+P(X=1)+P(X=2))=1-({20\choose0}p^0(1-p)^{20}+{20\choose1}p^1(1-p)^{19}+{20\choose2}p^2(1-p)^{18})=1-(0.00079+0.00684+0.027)=0.965$
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